My applause to you for wearing the baju kebaya when attending the malay wedding as well as the hari raya open house at the mosque. It would be more admirable if you had completed the look by wearing a selendang (loosely), since the mosque is an area where a female worshipper/visitor is expected to cover the aurat (modesty). I do appreciate your religion background, and of course there is no compulsion in you wearing one. However, it would look sweeter (lebih manis!) if you had wore one. That way, the malays/muslims around you would commend your sensitivity towards the sacred nature of the mosque.

I like to stress that there is no compulsion: it would be nicer if you wore one. I hope you don’t take this as a criticism Wearing the baju kebaya is already a sweet thing to do. Cheers!