In the case of
Cassia, yes seeing someone pronounce it wrong would make it like
Ashlynn and Neveah because to me it would signify that the parents just liked the sound and put some letters together thinking they were unique. However; in the case of
Johanna since the jo-HANNAH pronunciation is the one used most commonly in this country [assuming you're in the US] I don't think I would be as offended. It, for me, is just one of those names with multiple accepted pronunciations depending on the surrounding culture [like
Jesus,
Alicia, or
Madeline]