My children both have very traditional, very "old-fashioned" names, which have been shortened - think 'Elizabeth' becoming 'Beth' and 'Andrew' becoming 'Drew', for example (not their actual names!). However, the shortened versions of their names which their immediate family fell into using when they were babies... are not the shortened versions which their friends use. Think 'Liz' instead of 'Beth' and 'Andy' instead of 'Drew'. Which at the time, I have to admit, we didn't even take into consideration - both my ex and I also have very traditional, very "old-fashioned" names, which... have never been shortened. Not even by our friends. So we were unprepared for 'Drew's friend's mother, for example, asking if 'Andy' was available for a playdate (at the time, I remember asking if we were talking about the same boy, because I honestly thought she'd muddled him up with another child!).
Also, one of my godsons is called Aloysius - he insists upon everyone calling him Aly, because he hates that his parents bestowed that name upon him. And I have to look up how to spell it every single time I have to write it down (on their Christmas cards to the whole family, and his birthday cards mostly, because they hate that he shortens it at all!). So perhaps choose names which your children won't have to spend their lifetimes correcting people's misspellings of them, and be prepared that your Mya might be called Hermie, and your Sander might end up being called Ly by their school friends.
I actually like the names, by the way. Perhaps you could still incorporate them in as middle names...?