Thanks for taking the time to reply in such detail. I've recently proposed that we give blocks of time for working on issues raised internally (mostly improvements to our company documentation etc.) but have seen very little interest and even push back as there are other priorities, just as your describe.
With the little time we have for this work we've already achieved a lot but perhaps mostly on low hanging fruit. Many of the more substantial changes remain. People acknowledge the improvements it sadly doesn't seem to have driven any more engagement...