There is a cool technique on how to expose service cases on the customer site and make it look less alien. Apparently there is no much info on forum or docs, but a really useful academy topic on it. It shows how to overwrite some rules on RuleSet level, so there is no a lot of pxIsMashup in your code. Also it provides Clarity app that you can use instead of Cosmos/UI-Toolkit in the MashUp channel.

Clarity Mashup Input

Clarity Mashup Confirm