you cannot change a projects language after its creation.
so even if you were to change it in settings, it actually wouldnt do anything.
so if you see that js is selected for project a, it must mean that js was selected at the time of project a's creation (as tc does not have the functionality to switch languages for any give project).
unless, you are 1000% sure that you have been working in python in project a, and have been running python scripts in project a (for over a year), and somehow in the last couple days/weeks/months it suddenly changed languages by itself, then i would suggest filing for a support ticket since that is a never before seen bug where a project changed scripting language.