Hello Jon,
No, I really don't think so.
I am using group tags quite extensively and if they didn't work, my instruments would not function properly.
I do think your tags should be separated by commas though.
Here is an example:
<group name="Bourdon8" seqMode="random" seqLength="5" tuning="0.0" attackCurve="-100.0" decayCurve="100.0" releaseCurve="100.0" trigger="attack" tags="expression,Bourdon8,trig_atk">