It is a bit confusing because the menu is all in Latin...but on the side menu, if you click on number 18 (Lingua Anglica), it will take you to the page with English translations.

The translations are generally "eh, good enough", depending on what you need them for. A lot of them are from Samuel P. Scott's translations of Justinian's code from the 1930s, which, as the website itself notes, is "does not always meet the standards of a scientific publication". Some of the other translations are even older than that; some are more recent (the ones labelled "ARS" are from Ancient Roman Statutes, published in 1961).

There are some newer translations of Justinian's code, but I don't think they're in any online archives:

Alan Watson's 4-volume translation of the Digest (University of Pennsylvania Press, 1985)

The Institutes, translated by Peter Birks and Grant McLeod (Cornell University Press, 1987)

And Bruce Frier's 3-volume translation of the Codex (Cambridge University Press, 2016)

But hopefully you can find what you need in the English section of the Grenoble website.