Thank you for your reply! This adds clarity to my confusion regarding serverless tagging. This information would have helped a lot if it was included in the official documentation. You should considering sending the technical documentation team your post. I don't think it was clear that:
1. Job level tag can be used for cost tagging as an alternative to budget policy on serverless, but that it isn't recommended
2. That budget policy takes precedence on key value conflict. (Perhaps I could have experimented my way to this insight, but I rather have Databricks state the behaviour)
I should also add that AWS is moving in the other direction. From cost tags being whatever tag you want, to limiting to some reserved tags. I think this was change for the better as the poor select filter in the usage dashboard now gets overrun in Databricks and you don't risk different version of the same key (env vs Environment).
Regarding the second sub topic of Budget policy field missing from UI. I am personally using Terraform, but I think we should allow our colleagues to try asset bundles and ClickOps ourselves. You say it is more a display gap and limitation, than a bug, but could you ask them to reconsider their design here? It would be nice to quickly check if the job has a budget_policy or not in the UI without CLI or YAML. It somewhat makes sense that you can't modify the asset bundle, but I think it would be better if it stated read only its current value in the same format as the rest of the jobs. Then you wouldn't have to think of all these conditional logic on when a budget is present in the UI or not.
Regarding Tags element inside Budget Policy showing blank, the tags now appear. I don't know if the issue went away or if it only happens on some conditions.