Hello Werner:

I have made some changes to Roundup that I think addresses your issues.

From the changelog note:
===
Fix issues with utf8 support in Roundup. By default using:

 utf8mb4 charset
 utf8mb4_unicode_ci collation (case insensitive)
 utf8mb4_0900_ci collation (case sensitive)

which are settable from config.ini. Sadly I couldn't come up with a way
to mange these from one parameter. Doing a compatibility lookup table
would have increased the maintenance burden and have me chasing MySQL
changes. So I opted for the easy path and have the admins (with more
MySQL experience) make the choices.

Conversion directions added to upgrading.txt. I don't have any good
testing for this. I was able to generate utf8/utf8mb3 tables and load
a little data and convert. However this is a poor substitute for a
conversion on a working tracker 8-(.
===

You can see the changes at:

https://sourceforge.net/p/roundup/code/ci/8b31893f5930cbea37031d49bd08a631d1b6b654/

If you can please review them and see if I missed anything. Your expertise
in this area would be valuable.

Thanks and have a great week.