Hello there, I have a mare (horse number:16239126) tested:

Im pretty sure black hides pearl.

No, there are classic Pearl (black Pearl, the terme is the same for champagne dilute) and smoky black Pearl too.

Ah then its cause you need the creme gene. I knew it was something wonky with the pearl expression

Not exactly, the pearl gene is recessive ans need to be homozygous to express itself (without cream). Because it's on the same locus than the cream gene, there can be only two alleles for these two genes, meaning that a horse can be prlprl, Crprl or CrCr but not CrCr Prlprl or CCr prlprl, because it would mean 3 alleles on the same place, and that's impossible. Where you're right is that a single pearl allele will need a cream allele to be expressed, or another pearl one.

Homozygous Pearl for a long time was thought to only show up on red (ee) horses, the game reflects this. I believe this was simply because of how rare it was and a lack of DNA testing caused the few that were out there to slip through the cracks as champagnes (especially in the US).

Yes, it would be good to update this, at least the names of the colors.

It may not be possible to do so, as it would change the genetics of some horses, and their offspring.