The counters in the achievements tab stop counting as soon as the number required for the golden achievement is reached.
That is demotivating as soon as you've reached that point. Especially as soon as you achieved ten victories on a specific map, it's not so motivating to continue playing that map.

Can you make the counters continue?
So for example in case you've killed 755 enemy units with naval units, it would look like this:

Agreed - that would be even better (but higher development effort, which is why I hadn't proposed it).

I would be content with one extra level (platinum or diamond design) which requires 10 times higher numbers than the gold level.
That should be sufficient for as good as all players.