Awesome! Thanks for sharing.
The WIP limit you are missing can be implemented in many ways; one is to limit the number of task/issue each person is working at the same time. There’s probably nothing that helps you with that in the tooling either, but that is easier to keep track of (and becomes a question of conscious) than limits per column.
One cool team I met had this as their wip limit:
Never code alone!
Pretty cool. Super easy to keep track of.
Also, with this flow that you are describing you probably (or should not) have many things going on at the same time anyway. This makes it easier to keep track of your WIP so that it doesn’t increase without your knowledge.
Thanks for sharing. Keep rocking that kanban-thing!