You could do what you’re doing, but write those choices to a column in the User Profile Table. Once that’s done, you should end up with a comma-separated list of tags in the current user’s row in the User Profiles Table.
For your form, create an action “On submit” that sets a column value — set the “Tags” column for “this item” to be the column from the current user’s User Profile row.
I’d recommend clearing this value after the form is submitted so that each time the form is opened, the User is starting from scratch with regards to tagging and their previous choices aren’t copied to all form submission.
I use this method for selecting images in an inline list inside a form screen here: How to: Select an Image as a Choice using inline lists in forms