Firstly Topaz Studio is not, and never has been promoted as, a replacement for any Adobe products. Should you be looking for Photoshop type replacements there are quite a few out there such as Affinty Photo, Paintshop Pro and Gimp, a free pixel editor.
Topaz Studio is a artistic expression studio where you can create works that use your artistic vision. Topaz Studio does not manage your workflow and make minor image adjustments it is focused on creative photo editing only with a range of Stylistic and Creative filters but does have basic image editing tools.
In the case of using Topaz Studio as a plugin there is nothing convoluted about the Accept and Cancel buttons: Accept is the same as Save [back to Photoshop], or other host editors, and Cancel to Cancel editing in Studio and return to Photoshop …
