Registry still stores your email/password in plain text, so you probably shouldn’t share images of it. Also don’t mess with any other setting, registry is pretty powerful and can screw up many things.
You also need to restart to have the effects be applied.
Press windows + r and open
Computer\HKEY_CURRENT_USER\Software\DECA Live Operations GmbH\RotMGExalt
The only numbers you need to change are these (this is what it looks like for 50%).
Some common values
25%: 39 40
20%: 34 40
15%: 2e 40
10%: 24 40
5%: 14 40
If you want to figure out others you’ll have to figure out https://gregstoll.com/~gregstoll/floattohex/
And if you’re wondering about the ToS of this, Deca Support themselves have given fixes for Exalt bugs using Regedit. It’s fair game until (and if) they say otherwise.
now with deca’s stance: https://www.reddit.com/r/RotMG/comments/ihr0wv/you_will_not_be_banned_for_changing_opacity/
got some info on this from /u/Azebu and /u/Deivixo