The first issue clearly states that the custom models and views have not been registered with DXA. You'd have to create a class that extends AbstractModuleInitializer and register all views and custom entity models. For your setup you should have something like this:
public class ...
I did try to reproduce this issue in DXA 2.2.5 Java, but it couldn't able to reproduce this issue, it actually works for me in the OOTB DXA Core module as expected. same I also try to reproduce this issue in DXA 2.2.9 .NET there also not an issue. It's working fine, I can confirm that DXA Webapp Framework not having an issue for the multi-value field for ...
Bug is confirmed by SDL/RWS:
8.5 + DXA 1.7 -- issue not present
8.5 + DXA 2.0 -- issue present
9.5 + DXA 2.2 -- issue present
I don't know if they will fix it in the next release; DXA is not actively supported by SDL/RWS.