Troy, congratulations on trying to acknowledge both sides of your heritage!

Now, methinks that you are analyzing this too much. First, your Cornish national kilt is a regional/district/national tartan, so there should not be any problem with pairing it with whatever accessories you would want, even if from another country.

From the other side, you are entitled to wear the Clan Home badge, crest, etc. based on your heritage. Since you can wear whatever tartan you want (just see the posts on this board), there should be no issue from that point of view either.

Finally, unless you live in an area with Clan Home police or militant Cornish supporters, I would not worry about it. I have run into very few people that can look past the kilt, let alone recognize any accessories I might be wearing.