There's a reason why I asked for a "before save". Also given I don't know where the flag controlling the trainer card is stored, seeing a save like this doesn't really help me. Anyhow, I could not replicate the error you supposedly experienced.
Supposedly, if the error works the way you described it to be, with the forest randomization being the culprit,
if I used your save (gold trainer card), and re-randomized the forest, it stands to reason that it'll no longer be gold right?
Well guess what: it's still gold.
(Your randomized area, VS me re-randomizing your area) [this is to show that I indeed re-randomized the forest]
I also tried to randomize the forest on a save of mine, and my trainer card is fine. Can you find a way to replicate the issue, cause I can't.
edit: Given I can't downgrade the card via Forest Randomization, I think it's likely that it's some other edit that triggers it, or it only works on Black/White level trainer cards.