"merusakkan" juga boleh, nggak?
"This bus delay happens because of the rain that damaged the road."
Normally we say "...because the rain has damaged..." or even "...because rain damaged..."
I think the bit you are talking about is fine. You can remove yang to get what you want.
My issue is with "happens" as that normally would just be "is" or "happened". But "terjadi" is there. I feel it is more "happened".
"The" on rain is optional too .
I think a better version in English would be: "The bus was delayed because of the road damage caused by the rain."
Aaaagggghhhh Bis is acceptable - it keeps rejecting it. And the frustrating thing is that when you hover above bus - it gives both bus and bis as translations - for god sake be consistent