Seems there are no takers ;)
I'll take it to the dev list (I've confirmed this error on 2.5RC3 as well); if I get no reply there I'll file a bug report...

--- In firebird-support@yahoogroups.com, "realjimbeam" <realjimbeam@...> wrote:
>
> I've stripped down the database in question and tried inserting the value 1 instead of Systematic exposure in the record in TBLEXPOSUREPROGRAMS (the offending record). If I use the number, it works, indicating this really is a character conversion issue.
>
> If I insert Systematic exposure using isql.exe instead of Firebird, and run the view, I get the same error.
>
> Am I somehow inserting invalid text? Systematic exposure doesn't strike me even as weird ASCII, so it must be perfectly acceptable Unicode?
>
> Should I file a bug on the Firebird tracker?