I like it, especially as a nod to his Czech spelling.
You will have to correct/confirm it endlessly. All my children have perfectly ordinary names but ds uses one of the less obvious diminutive forms of his as a nickname, dd1 has a name that can be pronounced in two different ways & dd2 has (like izaac) a slightly different, European spelling to reflect a grandparent's name.
It's all fine & I don't mind at all that people get them wrong, but I do feel a bit awkward having to constantly say 'actually it's shortened/pronounced/spelt like this'.
Not saying that should put you off, but you are signing up to years of it...