While I can see the possibility of your first suggestion being helpful, I think that it might cause problems for those of us that are used to it working in it's current method.
Ehm... what's the current method? Tab-ing to the OK button? Would be much better if you could tab the code instead.
A hole remake of the editor wouldn't be wrong, with syntax highlightning wich could be modified in a local file by the user... but that's another story.
Regarding your 2nd suggestion, if there's a problem in a script (an actual scripting error, rather than a logic error), in my experience, the name of the script, line number and type of error are reported in the status screen, which, if I'm understanding your suggestion correctly, would just be a duplication of what already exists.
Well, that wasn't exactly what it should be used to.
For exampel if you give your custom function unexpected or insufficient parameters then you could trigger a error using this new built-in function I suggested to easly localize it and know in wich alias/function it resides.