I made a few adjustments to the post after making a few realizations from various commenters in the forum, thank you all!
A few weeks ago I made two dozen or so melee alacrity shards which brought the xp attainable down to zero. I realized that after two weeks of not crafting, I went back to craft, and low and behold the melee alacrity shard showed that it would give me xp!
One thing that I didn't mention between starting the post and making comments is that I used my free lesser reincarnation about two days ago. Before I retired for the night, I went to the crafting hall to see what I could craft, and I remember seeing that I could get full xp (relative to other shards at the level I was at) for melee alacrity.
So now my question is, if there isn't a mechanism such as xp/time restoration for shards (likely not plausible anymore), then is it possible that shards reset with all forms of reincarnation? I know that it works with true reincarnations, and I have used my free lesser reincarnation already.
I'm not able to use any form of reincarnation for about a week, and I don't plan on using a true reincarnation any time soon. I do have a need to use a greater reincarnation shard if at some point I can get my hands on one. I'll revisit this between now and then, but if anyone here knows that LR, GR, and TR Hearts reset crafting levels, let me know.