Lets see what we have with collation in MySQL. When you open phpMyAdmin, you have MySQL connection collation. When you open database, then Operations, you again have Collation setting. You then have same for each table and you have collation of each row that you can set under Structure.
What I have is utf8_general_ci in dashboard, latinn1_swedish_ci for database collation and utf8_general_ci for tables and rows. This is default and this is how WordPress makes it and it works without a problem.
When you install KC Settings and when it creates table wp_termmeta it is with latin1_swedish_ci and this is source of the problem.
I solved it by deleting this table, changing database collation to utf9_general_ci, then activation plugin again which creates wp_termmeta this time with utf8_general_ci.
So what I think you should do is follow WordPress way of creating tables with utf8_general_ci even when table collation is latin1_swedish_ci. People don't need to use phpMyAdmin for WordPress tables, why they should use for KC Settings?
Thank you for your plugin and your reply.