I think this needs a deeper conversation. I’m also in an inter-racial marriage. I’m eurasian and my husband is Indian. We decided on mandarin because my husband felt it would be more beneficial for them when they go into the working world. Personally, it’s a difficult language because we don’t use it every day but I help them however I can in my limited capacity. As for Bahasa, I feel that it is worth picking up and may be easier to pass too as it still uses the English alphabet for spelling although pronunciation may vary.
I am in mixed race marriage - I am indian. My husband is Chinese. We had my daughter take mandarin in school vs hindi as long term wise I think it will be more beneficial for her. It’s best for you to discuss with your spouse and see which language you think would be more beneficial for your kid. As we are surrounded by Malay speaking neighbours, studying Bahasa could come in very handy :)
I would go ahead with my instict as I am the mum and definitely its me taking care and guiding my child in homework etc . U can put your child for some tuition classes for malay language