Apparently somehow depending on the type of gateway, or on the type of forwarder software (like Semtech UDP or TTN MQTT), the gateway Traffic page(s) might show an orange Join Request. The application’s and device’s Data page will always show an orange Activation if TTN accepted the Join Request (including the new DevAddr). And the Traffic page of the gateway that was selected for the downlink will show the green Join Accept:
For errors see OTAA shows "Activation DevNonce not valid: already used" or Activation not valid - no gateways available.