Dear Contrary,
I just started playing again after a long long time and yellow/gold server was completely fresh for me, had nothing on it 3 weeks earlier.
On my profile I could merge red+blue/silver and only shown playtime for those servers. I got my cash and progress and stuff (i was in the middle of a brush on a route) but have 0 pokemons.
But I can confirm that the progress I made in the past 2 weeks on Gold is available, but as I said it was a fresh start.
Thank you,
Viktor