Element.KEYSIG

I was just a bit testing what I could do with a plugin.
Ok, my computer is a bit outdated, but as long as I don't use qml it should do it.

1. I tried to create a new score which should have the same parts as the current...
   The problem I faced here was that I did not find the correct instrument name to create the right parts.
   The instrumentId of a part gives some idea, but if I look in the .XML i find that there is no 1 to 1 realation.
   So if e.g. the instrumentId is "brass.tuba" the instrument for creation of the part could be "f-tuba", "eb-tuba-treble", "eb-tuba", "c-tuba"..... No idea how to select the correct one.

2. I created some score and wanted to place Key Signatures....
   var mykey = newElement(Element.KEYSIG);
   mykey.setKey(1);
   leads to:
   Unknown method parameter type: Key
   If I try to read the Key of the current score the result is similar:
   if (element.type == Element.KEYSIG) console.log(element.key());
   Error: Unknown method return type: Key

I crashed musescore multiple times when I tried to just add a KeySig to a score. (copied form another score).

I wonder how people could like to work with that kind of tool. It's a pain.