That is true, Swaminarayan is no incarnation of lord Krishna, swaminarayan is not god. swaminarayan established two gadi, Narnayan and Laxminarayan. In Narnarayan there are three murtis Lord Krishna radthaji and swaminarayan that means swaminarayan is nar and the Lord Krishna is narayan.
Did you read vanchanamurata? In vachanamuta swaminarayan said you should worship only lord Krishna. at list give the respect vachanamurta. and nothing is before brahma vishnu mahesh.