I got the requirement to capture Firefox customization in multiple customer discussions when we talk about application which need to be personalized. However, there is no direct working config available to achieve this. There have been some config available in UEM community and which used to work in past but due to certain updates in Firefox Appdata restructuring (I believe), it is no more working.
I have done Firefox profiling using UEM Profiler and found that Firefox creates a dynamic folder each time we launch the app and it leads to creation of unique folder for each user. To achieve this, I have modified the config to match the requirement of Firefox.
You can download the config file from UEM Community page where I have posted the solution for a users query and same has worked.