Based on the fact that 90% of our support cases are based on issues with saving target file, I think it would make sense to automatically try to save the target file during the project preparation stage. Simply one of the 10(?) steps that are completed automatically when a project is configured in Studio (or a single file, no difference).
This could be either a copy of the sdlxliff with pseudo-translation or just with copied source. Two things could be checked at this stage:
1) if there is an error while saving the file
2) how it looks - this would probably require adding a link on the summary screen "See the simulation of a target file for this specific document".