You’re running into a few known issues at once.
First, Momentary Buttons:
to replace any of those you need to change the device handler for those to Simulated Switch and either use SmartLighting Power Allowance or some automation to turn them off automatically after they’re turned on.
For SHM / STHM:
Do this: https://support.actiontiles.com/knowledge-bases/8/articles/8170-how-to-use-new-smartthings-home-monitor-with-actiontiles use these wherever you would have armed / disarmed the alarm in WebCoRE (I see you already did the Simulated Alexa switch thing. maybe that fits here?)
Now Alexa - that’s the toughest one. In the middle o fmigrating to NewApp SmartThings ALSO replaced the Alexa skill. I assume you moved to it. There’s LOTS of issues with it right now. I mean TONS. The best I can tell you is we’re all dealin gwith it and reporting lots of feedback to the team that’s on that component. For the latest see this thread:
https://community.smartthings.com/t/new-smartthings-alexa-skill-2020/
Short version - they’re working on it.