Is it ok to edit Plist files and use Programs such as Pacifist to install unsupported Apps in Mac OS

i have a question, i use my mac for music production and i have been struggling with mac os sierra in terms of compatibility of my music programs i have purchased over the years. i Did not want to let them all go and invest in new software all over again just because my mac os thinks its too old and also i have had many programs work but not work too well and buggy and laggy to some not even working anymore.

i have downgraded to mac OS Lion 10.7.5 and my programs are WORKING PERFECTLY, however some are not able to install, but i have found ways to get them to run by editing the Plist of apps and using a program called Pacifist.

My question is, is it legal or supported by apple for us to do these things, i mean i would not be asking these things if i was using windows, but Apple has a mind of there own and i was just curious before i go ahead and start doing this. i do pay for all my software so i don't download illegal programs or apps that i did not pay for. but i can't run my music software on Apples latest OS, and i find it too easy to just edit a Plist to run a app i have lol.

is it against apples terms and conditions, anyone know about these things. are we able to modify our apple systems, i would not call it reverse engineering but I'm not sure where i stand. (Why does apple make things so complicated)

i can understand why people just download programs without paying because when you pay its like they punish you for it later on.