The contra text —Numbers correspond in melody, with minor variants, to those of Lauda Sion.
2. Laudes crucis attolamus/ nos qui crucis exultamus/ speciali gloria.
Let us raise praise of the cross, we who exult with the cross's special glory.
3. Dulce melos pulset celos/ dulce lignum dulci dignum/ credimus melodia.
Let sweet melody knock on heaven; the sweet wood we believe is worthy of song.
4. Voci vita non discordet/ dum vox vitam non remordet/ dulcis est simphonia.
Let life not discord with voice. When voice does not blame life, the harmony is sweet.
5. Servi crucis crucem laudent/ qui per crucem sibi gaudent/ vite dari munera.
Let the servants of the cross praise the cross, who rejoice that through the cross they are given the gifts of life.
6. Dicant omnes et dicant singuli/ ave salus totius seculi/ arbor salutifera.
Let one and all say: Ave, saving tree, salvation of the whole world.
7. O quam felix quam preclara/ fuit hec salutis ara/ rubens agni sanguine.
How happy and beautiful was this altar of salvation, red with the Lamb's blood—
8. Agni sine macula/ qui mundavit secula/ ab antiquo crimine.
That Lamb without blemish, who cleansed the world from the ancient crime.
9. Hec est scala peccatorum/ per quam Christus rex celorum/ ad se traxit omnia.
This is the ladder of sinners, through which Christ, the king of heaven, drew all things to himself.
10. Forma cuius hec ostendit/ que terrarum comprehendit/ quatuor confinia.
Its form shows that it embraces the four reaches of the earth.
11. Non sunt nova sacramenta/ nec recenter est inventa/ crucis hec religio.
Here are not unprecedented sacraments, nor is this religion of the cross newly invented.
12. Ista dulces aquas fecit/ per hanc silex aquas iecit/ Moysi officio.
But it made the water sweet; by it the flit spewed out water, at the hand of Moses.
13. Nulla salus est in domo/ nisi crucem munit homo/ super liminaria.
There was no salvation in a home, unless the owner armed it with a cross on its lintel.
14. Neque sentit gladium/ nec amisit filium/ quisque egit talia.
Whoever did that felt no sword, nor lost any child.
15. Ligna legens in Sarepta/ spem salutis est adepta/ pauper muliercula.
The poor widow, gathering wood in Sarepta, won hope of salvation.
16. Sine lignis fidei/ nec lecitus olei/ valet ne farinula.
Without the wood of faith, her wheat and jar of oil would be worthless.
17. In scripturis sub figuris/ ista latent sed iam patent/ crucis beneficia.
The benefits of the cross hide under figures in the Old Testament, but now they are apparent.
18. Reges credunt hostes cedunt/ sola cruce Christo duce/ unus fugat milia.
Kings believe, enemies give way. By the cross alone, with Christ the commander, one soldier drives away a thousand.
19. Ista suos fortiores/ semper facit et victores/ morbos sanat et languores/ reprimit demonia.
The cross always makes its own stronger and victorious, it heals sickness and weakness, and represses demons.
20. Dat captivis libertatem/ vite confert novitatem/ ad antiquam dignitatem/ crux redemit omnia.
The cross gives liberty to captives, renews life to its former dignity, and redeems everything.
21. O crux lignum triumphale/ mundi vera salus vale/ inter ligna nullum tale/ fronde flore germine.
O cross, triumphal wood, hail the world's true salvation. Among all trees, there is no comparison, with its leaves, flowers and fruit.
22. Medicina christiana/ salva sanos egros sana/ quod non valet vis humana/ fit in tuo nomine.
Medicine of Christians, save the healthy, heal the sick. What human strength cannot do, happens in your name.
23. Assistentes crucis laudi/ consecrator crucis audi/ atque servos tue crucis/ post hanc vitam vere lucis/ transfer ad pallacia.
Consecrator of the cross, hear us present praising the cross, and after this life transfer the servants of your cross to [their heavenly] palaces.
24. Quos tormentis vis servire [= seviri?]/ fac tormenta non sentire/ et cum dies venit ire/ nobis confer et largire/ sempiterna gaudia.
Those you wish to be ravished by torment [I take "servire" ("to serve torment") as a copyist's error for seviri (saeviri)], let them not feel the torment. And when the day come for us to go, grant us eternal joy.

I provisionally offer the translation of "Msgr. Henry" (slightly modified):

Praise, O Sion, praise your Savior, Shepherd, Prince, with glad behavior, Praise in hymn and canticle: Sing His glory without measure, For the merit of your Treasure Never shall your praises fill. Wondrous theme of mortal singing, Living Bread and Bread life-bringing. Sing we on this joyful day: At the Lord's own table given To the twelve as Bread from Heaven, Doubting not we firmly say. Sing His praise with voice sonorous; Every heart shall hear the chorus Swell in melody sublime: For this day the Shepherd gave us Flesh and blood to feed and save us, Lasting to the end of time. At the new King's sacred table, The new Law's new Pasch is able To succeed the ancient Rite: Old to new its place hath given, Truth has far the shadows driven, Darkness flees before the Light. And as He hath done and planned it- "Do this"-hear His love command it, "For a memory of me." Learned, Lord in Your own science, Bread and wine, in sweet compliance, As a Host we offer You. Thus in faith the Christian heareth: That Christ's Flesh as bread appeareth, And as wine His Precious Blood: Though we feel it not nor see it, Living Faith that doth decree it All defects of sense makes good. Lo! beneath the species dual (Signs not things), is hid a jewel Far beyond creation's reach!

Though His Flesh as food abideth, And His Blood as drink-He hideth Undivided under each. Whoso eateth It can never Break the Body, rend or sever; Christ entire our hearts doth fill: Thousands eat the Bread of Heaven, Yet as much to one is given: Christ, though eaten, bideth still. God and bad, they come to greet Him: Unto life the former eat Him, And the latter unto death; These find death and those find heaven; See, from the same life-seed given, How the harvest differeth! When at last the Bread is broken, Doubt not what the Lord hath spoken: In each part the same love token, The same Christ, our hearts adore: For no power the Thing divideth- 'Tis the symbols He provideth, While the Saviour still abideth Undimished as before. Hail, angelic Bread of Heaven, Now the pilgrim's hoping-leaven, Yea, the Bread to children given That to dogs must not be thrown: In the figures contemplated, 'Twas with Isaac immolated, By the Lamb 'twas antedated, In the Manna it was known. O Good Shepherd, still confessing Love, in spite of our transgressing,- Here Your blessed Food possessing, Make us share Your every blessing In the land of life and love: Thou, whose power hath all completed And Your Flesh as Food hath meted, Make us, at Your table seated, By Your Saints, as friends be greeted, In Your paradise above.