Ask the bride and groom. If it is a very traditional family, maybe ask the parents instead...

As for kilts at non-Scottish weddings, I've done it.

A friend who is East Indian by way of Trinidad had a big Hindu wedding and, when I asked about the kilt, she told me that traditional clothing was very appropriate. I wore the kilt and was the only one, but many people were wearing Indian attire. There were a couple nice conversations with folks about the importance of honouring traditions.

Last night, I went to the wedding of longtime classmate from kung fu. He and his bride are Chinese but they are also devout Christians, so the wedding was more Western. Knowing him and his family, I judged that a suit would be more appropriate and didn't bother asking about the kilt. There were hardly even any people wearing traditional Chinese clothes.