The issue is/was the change in PostgreSQL versions rather than the OpenACS upgrade. As Claudio wrote, the recommended approach is first to upgrade with PostgreSQL 8.* to OpenACS 5.8 and then dump/restore in PostgreSQL 9 and continue.
https://openacs.org/xowiki/Postgres_9
We did not adapt the kernel update scripts for pg.9 since this would break upgrades for installations with earlier OpenACS/pg-versions (there are really many old and working installations in the free wild). The easy rule is that with OpenACS 5.8, the support for PostgreSQL 9.* begins.
I can't comment on the the language issue, but you it seems from your comments, that this was a local configuration issue.
