Hi Patrick,
Congratulation on the progress of your restauration project.
I beleive that the flat F# can be found in most German flutes also, at least the ones where the cross fingering for F XXX X0X is working.
I think this is an inevitable trade off. For the cross fingering F to be in tune, the flute maker must make the F# flat (French and most German flutes). If the F# is made in tune then the cross fingered F is sharp (english flutes).
The continental flutes rely on the player to open the F key to have the F# in tune.
In the traverso, the compromise is generaly different. The F# is made slightly flat and the cross fingered F slightly sharp and it is up to the player to adjust the pitch by rolling out/in the flute. This is easy on a traverso because thanks to the small embouchure and tone holes they are very flexible.
I could be wrong and maybe one of our prefered flute makers on this list will confirm or infirm this… 