AkiraKiri So, the Universal bank for server and custom games script you linked above was actually how i got my start on trying out bank scripts... it was great and it is unique in that it stores it's data in the player stats file so it goes with you to other servers but you can only access it on servers THAT ALSO RUN THAT SAME SCRIPT so it will still only work on servers you play on has that script installed.
After using that mod on my servers for a while, i figured i would create my own for the learning process and to overcome some of the unique limitations that script has (not because of poor coding, but rather limitations with the player stats variable).
So while my version of the banking script is persistent across all MY servers (t5 and t6) it is only because all my servers share the same database for player data and stats. So it is similar to the script you linked in that it only works on servers that have that same mod / database (just mine).
SO... If you are looking to create a bank that works on all public servers, that obviously isn't possible... you would need each server to run the same bank mod... i think the universal one by Jezuz is the closest we'll come to that because he made it so ANYONE who installs his mod joins their server to that universal system.
But if you are looking to create a bank that will work across all of YOUR servers, you have lots of options depending on how you want to store the data... Find me on Discord (same name) and i can help!
And others have mentioned... don't use AI... it's not the best at guessing and will lead you down the wrong path 
