Tux editor should not give up saving even on shaky internet connections.
Actually, it can easily try forever without doing any harm.
So as to not block a translator doing as much work as he can, translations
can be queued and transmitted as soon as there is an opportunity, while
requests of supplemental and help data can be dropped, and their state be
reset to "never touched" once the editor moves on to another field.
There seems to be a basic implementation of the functionality that we likely need:
https://serviceworke.rs/request-deferrer.html
I did not read many details, and there is likely some error handling to be added,
but that should not be too hard.
See also (past work on related matters):