Then I'll continue to do as I've been doing, I deleate the entry from my library and add the item again from the source sites, carefully selecting the collection I need to keep them in...
Please consider devoting sometime for working upon accessibility features in near future, I will contribute (of course with zero technical knowledge) for improving screen-reader accessibility as an end-user in all possible ways.

I am also a screen reader user. I enjoy using Zotero a lot however, this lack of small set of keyboard shortcuts makes it so difficult to use. Many of the features of Zotero are great. However, just these small things that I think are very easy to fix are a very bad bottleneck for its usability for screen reader users. Moving and copying between collections or moving collections from the left hand pane using keyboard is very critical for screen reader users. Please, please fix this. I swear it is not technically hard at all.