I live in a fairly (but not very) Welsh-speaking area and nobody with raise eyebrows at Maldwyn. No worse than Meurig, Emrys, Eryl, Llyr or the more fashionable Mabon, Eban/ Efan, Cai, Iolo etc. The advantage is that Mal is quite a cool nickname.
God these names are a pain to type with the English autocorrect on 