When entering new transactions, and when exporting transactions to CSV, having multiple subcategories with the same name, such as "Work Expenses", but different Parent Groups, such as "Me vs Partner" causes confusion.

I'd vote against this change. It can be really useful as-is for certain groupings. For example, I often type "inc" when categorizing to bring up the income categories. The current behavior is also how it works in YNAB: The "which are not selectable" point in the original comment is valid though. YNAB handles this by shrinking the text size of the category group names, as you can see in the above screenshot. Maybe this Issue could be modified to be a UX change (shrinking the category group name text) instead of a functionality change, such that it's clear the category group names are no selectable.