That would mean that all the translators loose the revision comment connection to the version their translations used to be based on. Isn't that considered to be a problem?
No, because of the reason you give yourself:
I would not be much scared to step further with the delete+add approach, since this is a loooooong outstanding TODO item, and the install part need restructuring anyway, as it was discussed countless times. So the version association would be lost anyway because after the restructuring, most of the translations will become unusable for building anyway, and would need to be brought in sync.
I am currently on doing minor fixes in the begining of the manual before the installation part, and then I will put up a plan on how we can restucture it on the XML level, without too much hassle for the translations teams.
Goba
