Discovered (in G3 3.0.2 (3042)) when you set your own value (in my case 120) into “Command” save the file, open it in Glyphs 2 (because you want to use some old scripts), save it and open it again in Glyphs 3, the Command is set back to 100.
Does Glyphs 2 write its standard values back into the file?
I assume G2 simply does not write it into the file. Going back and forth between G2 and 3 will lose the value.