Have you checked your app store? "Poorly engineered" covers a lot of territory and you may need several different apps to make up what you feel is a "well engineered" product.
Once a mix is laid down, however, you cannot entirely separate individual instrumental tracks or even discrete frequency bands without affecting others.
I would begin with something like Audyssey; https://www.google.com/search?q=audessy+for+mac&rlz=1CAACAJ_enUS693US694&oq=aude ssy+for+mac&aqs=chrome..69i57.3344j0j1&sourceid=chrome&ie=UTF-8
It exists as a DAW (digital audio workstation) which means it can be rather complicated. Complexity does have the advantage of dealing with multiple issues.
Thanks, I have that app not sure where to start. Heres a screen shot of a Beach Boy track 44100Hz 24bit not sure which filter to start with. I need a tutorial for this task{730075,Upload}