Hello , Congratulation for yourself costumize , recommendations to joycons : always disconnect the battery, wear gloves, the back cover is better changed if you disconnect 2 flexes from the rail connector
As someone who has taken apart pro controllers a bunch to clean the internals and has done a few joycon shell swaps as well, you did such a great job for your first time! I'm very inspired to buy some new shells for my controllers and maybe even some consoles toooooooooo!