You're really going back into the past!

I don't think I ever solved this directly, but I did solve it indirectly I believe, by using MultiMAME to basically trick MaLa into thinking the daphne games were really mame games, so they're all in the same list (emulator). I'm happier anyway because to me,
all arcade games should be together, not segregated into laser vs. non-laser.
A bit of a learning curve, but I'm happy with the results. I don't remember exactly what I did to feed it the extra metadata, but I think you basically end up with a super game list xml file (mame style) that has all the mame games plus all the daphne games, and then I either edited it directly, or else multimame had some provision for setting all of it when it generates the super xml file.
If you go down that road and have trouble getting it to work, let me know and I can check to see how I have it configured.