I don’t know if this is intentional or not, but collecting Big Melons (value of 5) or Gold Melons (value of 2) do not progress the any of the level’s “Collector” achievements at all. They add 0. Only normal melons (value 1) progress it.
Just collect a big melon or gold melon. Then view the progress on your “collector” achievement before and after to see it did not progress it.
I expected whatever value of melon to progress the achievement by said amount. So a big melon adds 5 to the progression, and a gold adds 2.
Neither big nor gold melons progress the “Collector” achievement, which makes progression a lot slower.
If really needed I can capture this on film.