I would normally refer you to the manual http://thingsthataresmart.wiki/index.php?title=Alexa_Helper, but you have some very interesting problems I could address here.
1 Alexa Helper can’t do anything with a switch that is NOT seen by Alexa. The thing I don’t understand it WHY it won’t discover it. The questions I would have on that would be:
-Did you add the switch in the Alexa App from the Play/Apple Store?
-Do other switches/dimmers work properly?
2 You refer to the switch by its SmartThings name. So, if you want to run the ST routine called “good night”, you would do the following:
-Create momentary switch called something like Night Mode. You can’t use "good night’ as that is a reserved word by Alexa
-Discover the switch via the Alexa App
-In Alexa Helper, create a control scenario and use the Night Mode switch as your trigger. In the routine area you would put in the routine.
You would say “Alexa, turn on Night Mode” and that should work.
Let me know if that works…