Not sure if this is answering your question, but I can use keyboard shortcuts concurrently with astropad’s stylus input: for example I can hold the spacebar pressed on my imac’s keyboard and at the same time drag my apple pencil on the iPad’s screen. In mischief app this successfully causes the canvas to pan. Or I can hold Shift+space on my imac’s keyboard, which allows me to rotate the canvas with my apple pencil. Just like I’d do with my wacom.
I can even set shortcuts inside Astropad and do the exact same thing without ever touching my imac’s keyboard - merely using the on-screen modifier and shortcut buttons inside Astropad for iPad.
What seems to be not working properly, is the following scenario: use the iPad’s on-screen “shift” modifier key, combined with my imac’s (physical) “spacebar” key - this combination seems to ignore the “shift”! The opposite however works: Using The “spacebar” shortcut on the iPad combined with the “shift” key on my physical keyboard registers as shift+spacebar - strange, but unimportant IMO!
tldr, as long as you use either the on-screen shortcuts xor the actual keyboard of your mac (and don’t mix), it’s working fine! hope this helps!