What transifex provides for translators is not under my control. That said, I have just posted links to a current master Beta2 build in the thread looking for Volunteers to update to User Guide.
That build is up to date (even with translations).
Transifex does typically list the source file and line, so it is easy to use Sigil's github website to see what/how that string is used.
See for example:
https://github.com/search?q=repo%3AS....%22&type=code
And it shows it is used in a Warning Dialog.