The moderators are mostly inactive considering that interest in speedrunning discontinued features has fallen off significantly. You can mention if you have a bunch of old pending runs in the #speedrunning channel in the Discord, it probably will get the attention of at least one of the moderators.

I really don't have a good answer to this. Of course you're not supposed to learn the seed of a random seed run until it's over, and downgrading can set the seed to 0 and erases whatever it was. This also is kind of a way to just break the random seed category because it becomes a set seed of 0. So maybe downgrades that destroy the seed shouldn't be allowed for random seed runs on that basis.

I would put player head as item as while it is a block, it has an item form. Only things that don't have an item form should be in the block category.

Sounds a lot like the Intel integrated graphics bug. Using a resource/texture pack won't fix it.