i would much prefer "mum" not to be used over "mom", its very distracting
unless its used to as distinct variation of "mom" in japanese then stick with "mom"
Mum is British English you dingus.
Moving on, I'm more bothered by the term 'landmine'. I know it's hard to translate 地雷 effectively, but isn't it exactly why you should romanise it instead of trying to find the correct translation? It's the same thing with ツンデレ、 先輩、etc. You don't go around trying to translate them, do you? Furthermore, the term as a fashion sense has eclipsed its usage as a type of personality in recent years. Another example would be trying to translate 派手子.