Don’t feel bad, because 9 times out of 10 it’s user error, or lack of knowledge, which is technically the same thing. 
Some of the previously installed AUR packages work others doesn’t. For example when launching SchildiChat it gives me this error…
Could not find the program '/opt/SchildiChat/schildichat-desktop'
While LibreWolf works fine.
I think reinstalling/rebuilding each one would be the solution for those.
How do I list down which ones I previously installed from AUR? Or rebuild from system, if already present?
pacman -Qm
Thanks reinstalled/rebuild all of them.
What’s this kdewallet? Is that a new app from KDE? Always asking for password when I open certain applications.
Just click “OK” without entering a password, then select blowfish. It will stop asking after that.
You may need to delete .local/share/kwalletd first, then do the above, so you might as well just delete it first.
It’s unimportant (for the most part) and gets recreated automatically.