About the Shimejis:

Yes, a good portion of them are faulty.  If I remember correctly, the list of callbacks include:
Gamzee's picture files were too tall and therefore he looked like he was crawling everywhere, when he actually did crawl he became nearly invisible (This was known before I released them, however me in my faulty mind thought: Hey!  Maybe it's just my computer! However, I tried it on my mom's computer recently and discovered that it doesn't work on there either.)
I uploaded the wrong files for Mexikat and Terezi.
The animations were limited and not really that good.
I forgot Nepeta's tail in several frames
In a walk/crawl frame of either Eridan or Gamzee (I forget which), their sign is replaced with the Cancer sign (due to the fact that I used Karkat as the base for each new one that I made, and in one frame of laziness I forgot to draw over his sign.)

What I will be doing about it:
THIS IS THE BIG, MAJOR, TL;DR FIX: I will be remaking ALL of the shimejis that I have previously made, as well as finishing up the trolls, possibly adding some extra troll outfits, and from there I'll go to Beta Kids -> Alpha Kids -> Random Requested Chars.  This will take a LONG time to get done with, however.
I will be drawing Gamzee's horns more squished down, seeing as they were really the only reason that they took up such a large amount of space in the first place.
I will be differing from the original Shimeji body style which I just copied for my use and using ones that I make myself, therefore offering a more differing style and a greater range of motion.
I'll take down Mexikat and Terezi until I can get their replacements up.
I'll leave Nepeta up for now, but she will be replaced like the rest when her updated version comes out.
Same as above goes for that Eridan/Gamzee.
I'll do them in the order that I did them in the first place: Karkat, Terezi, Gamzee, Mexikat, Nepeta, and then Eridan

Things I possibly may improve upon:
I may write scripts to make more motions common for certain characters, like Nepeta jumps around more often and Eridan just sits and mopes more often.

Okay, thank you all for your patience with my ignorance.