'new_empty_row' is deprecated and is provided for compatibility only,

Downgrading to a version of HTML::FormFu::Model::DBIC older than 0.04000 (2009-04-22) will get rid of the deprecated warning. Or you can just ignore the warning.

compare_relationship_keys is a private method

Downgrading to a version of HTML::FormFu::Model::DBIC older than 0.05000 (2009-05-26) or downgrading to a version of DBIx::Class older than 0.08103 (2009-05-26) will get rid of the private sub error. (It's very harsh to use carp here!)

Deep recursion on subroutine "HTML::FormFu::base::render"

That's most likely a real problem, and there's no superficial workaround. (Although downgrading the dependencies to avoid the other problems might avoid this one as well.)