This might be a problem with a resource optimization, those methods can be actually renamed by the JS minification compiler.
But personally I don't believe that.
This might be caused by mixing some jquery versions how you mentioned. We have namespaced RichFaces' version of jQuery in 4.5 and 5.0, but I would recomend to use just one version on the page.
You are right to remove jquery.js - it will conflict with the RichFaces jquery.js (resolved in an upcoming release, see: RF-12936).
Additionally RichFaces packed.js contains some jQuery UI scripts. So by including the entire jQuery UI minified file will introduce conflicts. Have a look at the RichFaces source tree to see which jQuery UI script you should exclude: