Problems creating a unit (AoE2HD)

It’s not DE, but I’m hoping some of you guys can help me. So I’ve been trying to create a hero unit, first time modding, just for fun; I didn’t even bother creating a mods folder, directly editing the game files instead, as I already made a back-up anyway. Thing is, so far things’ve worked, edited Joan d’arc just fine, cloned a Heavy Scorpion, and edited key-value-strings-utf8 to change it’s name too. Thing is, when I tried to make a completely new unit, this hero I was talking of, while it’s name and stats appear in the scenario editor correctly, it appears without an icon, isn’t visible in the game, doesn’t make any sound when spawned, and isn’t able to be deleted (not that I know where it is, but I’ve tried), yet it is in the game, as I see it’s blue dot in the map. It should look like a Centurion, I made sure I input it’s graphics correctly, ID 7610 (8050 for the .slp file), yet it’s unusable. Why is it? How can I fix it?

After experimenting a bit with Advanced Genie Editor, it seems I am unable to edit icons and sprites, and the lack of a sprite may be the reason for this “ghost unit”. I’ve tried changing the icon of the Heavy Scorpion, and standing/walking/attacking/dying sprites, but, although AGE correctly edits it, the game still shows the Heavy Scorpion as usual. To top it off, it seems that the problem isn’t with the key-value-strings-utf8 file, either, but something different. As if hard-coded, the Heavy Scorpion I copied from the original, and then edited its stats, works perfectly, besides the icon and sprites thing; however, if I create a new unit, and then manually copy all the Heavy Scorpion stats on it, it has the same “ghost unit” problem that my hero unit has. Could that be the case, that unit icon and sprites are hard-coded into the game? If that’s the case, how could I edit it?