Is there a way to install Photoshop Actions from a previous version onto the current?

Interesting. I just loaded actions created in CS6 into latest Photoshop. No problem, no warning. I am on Windows but that should not be in question, actions works on both systems without any problem. Can you upload actions somewhere to test them? Perhaps that is Mac issue with newest OS?

Curious... I just saved an action (not complex) from Mac CC 2018 and Windows CC 2021 loaded it without any issues.

So, I have 3 ideas:

1) I can try resaving the action for you

2) Using xtools, you can save the action as an XML file and convert it back to an action:

https://sourceforge.net/projects/ps-scripts/files/xtools/v2.3/

3) You could try one of the following (I have not personally tested these apps, so execute them at your own risk):

http://www.kyrsoft.com/articles/atn-translator-windows/

http://www.blinkenbyte.org/modifyatn/modifyatn.html

Good luck!