Great stuff, good work.
One of the annoyances I have with GOG, is the lack of correct year for a game, or only the year of release at GOG or remaster etc.
PCGaming Wiki can certainly help with getting all the years, provided you know what game title to query with. I've yet to find a full-proof way to fully automate this, so perhaps you could look into this also.
EDIT Here is an example, though admittedly a special case.
https://www.gog.com/en/game/nitro_racers https://pcgamingwiki.com/api/gog.php?page=1747488431 gets you to
https://www.pcgamingwiki.com/wiki/Nitro_Racers But note the year of release is 2022 ... no date at GOG, except for copyright mention near bottom left of game page.
In this case, the game was never released, except as a demo back in 1997, as reported by Wikipedia.
https://en.wikipedia.org/wiki/Nitro_Racers The game is clearly from 1997, despite only being released on GOG and Steam in 2022.
You'd think GOG would want to help promote an old game by listing the year it is from.
At least this game sort of has an excuse, if not a very good one, but many other games at GOG don't even have that.
A game at GOG should always have the original date, along with where warranted a more recent release date.