Depends on how tech savvy the team is. I believe it can be fixed by doing the following. If I had more time, I would set it up in 7, do a test migration to 8 and see if it works. Maybe somebody else can verify:
In Paratext 7, the data was in a subfolder of the project folder that is called: Interlinear_{ProjectName_LanguageName}
When migrated to 8 the name of the folder was changed to: Interlinear_{LanguageCode}
Rename the folder to match the language code of the language you are Interlinearizing in. “en” maybe?
Then, in that folder is an XML file for every book. At the top is this line:
<InterlinearData BookId="1CO" GlossLanguage="fr" ScrTextName="ffmDBL">
Change the GlossLanguage to match the LanguageCode you used in the folder name. Do this for every book.
Now, when you set up interlinearization, you will select a model text that shares the same language as your gloss (but be careful, it must be exactly the same, could be en-US or just en). The old data should show up again.