https://github.com/stellar/bridge-server/blob/7a0a8f0444e7e83d67251aadb635ad3a64cb9f32/src/github.com/stellar/gateway/compliance/handlers/request_handler_send.go#L274

If other FI's compliance server returns 202 "pending" or 403 "denied", it will return InternalServerError as the if condition is != 200 only.

It should be:
if resp.StatusCode != 200 && resp.StatusCode != 202 && resp.StatusCode != 403 {
...
}