Reflection and tagging kills
Reflections most definitely do count. The way reflects work is the game takes the skill reflected, applies your stats to it, and tosses it back at the caster. This produces some interesting results, such as getting rifle/bow kills with a Mesmer.
Have you seen white numbers pop up on your screen?
IIRC, karka have a horribly low drop rate to begin with. Might just be bad luck.
Reflections do mark yourself as the new projectile owner. That’s why you create a clone of yourself when reflecting Ether Clone, or teleport yourself when reflecting Dark Path. So it would be very strange for it not to tag. It is more probably just a case of “not being lucky with loot”.
Did you get XP ? It’s the best way to determine if you tagged (well, except for getting a rally, but most people try to avoid getting downed :P ).
Getting xp, so prob just rng, thanks for the help.