I am wondering if the issue is this:  The replica IDs for the forms9 and forms9s templates are the same as the templates on servers with an earlier fix pack, and they have received "updates" from an older version of the template?  You might need to change the replica ID of the forms9 and forms9s templates before bringing the server online.  

Daniel Nashed blogged that the solution he had found for a client was to revert back to the forms9 and forms9s templates on a FP6 server.

http://blog.nashcom.de/nashcomblog.nsf/dx/inotes-borken-with-german-locale-with-9.0.1-fp7.htm?opendocument&comments#anc1

Or just certain languages? Daniel Nashed's blog implies the German version, but English 'should be OK' - are there other languages affected?

Thanks!

Daniel Nashed said that it is not reported to affect English. Apparently, the error is easily reproduced if it is a problem for your locale. 

In Technote 1991039, IBM says that you can "[c]hange the decimal separator from a comma to a period in Control Panel -> Clock Region and Language -> Formats -> Additional settings -> Numbers."  This means that you would keep the German locale, but with this tweak. The link to the technote is available here: http://www-01.ibm.com/support/docview.wss?uid=swg21991039&myns=swglotus&mynp=OCSSULMR&mynp=OCSSKTMJ&mync=E&cm_sp=swglotus-_-OCSSULMR-OCSSKTMJ-_-E

Any news about fix to that issue?

An interim fix was released on October 4th:

https://www-945.ibm.com/support/fixcentral/swg/selectFixes?parent=Collaboration%2BSolutions&product=ibm/Lotus/Lotus+iNotes&release=All&platform=All&function=all