OK, you've posed a number of RegEx challenges. The easiest way to solve this is for your post, in a Code Block, a real-world example of ALL possible cases that you expect to encounter. And, although you have mentioned some rules in the above text, it will help to understand if you can LIST all rules together.
Your Questions from Prior Post
Actually, from what I've seen and posted, KM is copying to the System Clipboard, not a Named Clipboard. If you want to remove the last copy to the System Clipboard, just use this: Delete Past Clipboard action with "0", which means the last or current clipboard entry.

It is not a problem per se. I use "Local" variables so that the global Variable list is not cluttered. "Local" and "Instance" variables are auto-deleted when the Macro in which they were created finishes. The only reason to NOT use "Local" variables is if you want to retain the Variable value for other Macros, and subsequent executions of the same Maco. See KM Wiki: Variables .
I don't understand your question, or what the objective is. Could you please clarify? Maybe post the manual steps you use to accomplish the task. If it is complicated, then a video or animated GIF would be great.
If I have missed any other questions, please feel free to repost.