First, I have to say that I really like your mountains, in both versions.

If realism is what you're worried, in my opinion in this kind of maps is actually acceptable that the proportions may be slightly altered: for example, the icons of the city, or the trees are always a little larger than they would be if all was really proportionate.
If it is a matter of general harmony of the map, in my opinion, to decide on the size of the mountains you have to consider how you draw the other elements and what size they will have.