Did I set myself up for trouble? Mixed collations in db.

I created a user registration database from the User Registration Solution and imported the db, which is InnoDB and latin1_. My current tables, which will have recordsets on the same pages are in MyISAM and utf8_.
A couple of my recordsets are using JOINS between them. Everything is working at the moment but as I began to create a couple new tables it accured to me that if there is reason for one or the other, or if I need to convert the older tables, I should do it now.

Neither of my older tables are setup with foreign keys. That was my original intention when I set those up, but now they just use JOINS and WA Manage Relational Tables.

Should I leave well enough alone or should I do something now?

Thanks,
TroyD