Welcome! 
Yeah, the short answer is that both of those devices were really intended for a Z wave only set up. And smartthings is a multi protocol set up. So they don’t work out of the box with smartthings because they rely on some Z wave-specific options which smartthings generally doesn’t want to use because then the device will be limited in the other devices that can work with on a smartthings platform and that confuses everybody. 
Also, both of those devices are old technology at this point, which also introduces some complexity.
So… To get them to work you have to use custom code, and as you may be aware, smartthings is in the middle of a big transition to a new backend platform and a new app and some of the old custom code that worked with the old app doesn’t work with the new stuff. Somebody has to rewrite it, but in many cases the original authors may no longer be supporting it, so…
Yeah, it’s tricky.
Hopefully you will get some responses to this thread from people who are using those devices with the new app, I just don’t recall seeing anybody who had them working yet.
As far as replacements, many of the multi button devices have run into the same issues with the new app. Again, hopefully someone who has something working will chime in.
One option which does work is to use one of the dashboard apps on an inexpensive WiFi phone. This is popular for scene selection. So I’m going to link to a recent discussion thread about those:
Sharptools , actiontiles or native ST app for your wall panel? (2019)
note: @tgauchat was a developer for one of the third-party dashboard apps and has a number of posts in that thread. Sadly he passed away a few months ago. If you have questions about any of his posts, you can go ahead and reply to them but tag @625alex so you can get an answer.