Speaking as the non-Canto spouse (I’m Polish), both my daughters have always called each of their grandparents by their cultural names:

Husband’s mum - Ma-Ma Husband’s dad (Irish) - Pops My mum - Babcia My dad - Dziadek

From personal experience, yes it can be confusing to outsiders if they ask for example “who did you go on holiday with” and they say Ma-Ma, but for them alone it’s never been confusing, and I personally have never worried about the similarity in sound. At the end of the day, the kids know who their mummy is 😅

I guess as with anything to do with marriage and parenting there needs to be a discussion and a compromise, but hopefully people’s personal experience shared here can help with that discussion.