Ok. normaly I put a plugin and its working, if not there must be a note. For this i had to search a lot…
You mention some scripts and do not clearly talk about where to put a script and what for?
How many function.php can I find in WordPress to put some code? I tried and found no difference, so technical matters can be various, but somehow a user finds out, plugin is working or not working. So why there is no clear solution, even on different topics. I did not understand what to do – and spent a lot of time before with loco yet…