While I understand, I think I would go away from the wording “character” as this is really misleading for the definition of a stored Password ( without a deeper description) . ASCII/ECBDIC are using 7 Bit’s only, Extended ASCII 8 Bits, UTF between 1 and 4 bytes - and all are representing “characters”.
Especially as there is a lock after a number of retries, it is essential to describe this.
Look at this post where the user has used total wrong “characters” and now is a bit lost … ( I would say he is sitting on 59,- Euro crab as he can’t reset the keys any longer )
Anyhow, your turn how easy you like to make the usage of your products 