Not available yet. The importer screen at /forms/import/tally is built (lane forms-x01, row F-X01; PR finocket #6057 for its database change) but needs database changes applied at release and has never run against a real Tally account. Nothing below can be used today.
What comes across from Tally?
Forms, their blocks, simple show and hide rules, settings, and submissions with their answers. Imported forms are unpublished drafts so you can check them first.
What does not come across?
Jump-to-page, required and calculate actions, nested rule groups, formulas, payment credentials, file contents, signature images, styles and the form password. Each is reported as a warning.
Is my Tally key stored?
The key is used for that import only and is not saved in the database or repeated in errors.
Can I run it twice?
Yes. Each record keeps its Tally id, so a repeat updates what is there instead of duplicating it.