Well when I played the self-employed writer track it wasn't counting royalties towards experience, and that was a couple of weeks ago at most. I did manage to get her all the way to rank 10 but she was well into her elder phase by then (personally I feel it's not so much bugged as badly scaled, if the figures were a little lower so that progression was in line with say painting, the lack of contribution from royalties would be a non issue). That said, at the point where she finally clawed her way past the line she was getting something like 90,000 simoleans a week in royalties, so the lack of career progression wasn't exactly holding up her ability to earn. If you do go the self-employed writer route, may I heartily recommend the Entrepreneurial Mindset reward, it doesn't look like it should make a difference, that is to say, the figure listed as simoleans left until next level doesn't change when you get the reward, but it actually does speed up progression, basically each one simolean you earn reduces that total left to go by more than one (I don't know exactly how much by as I wasn't counting that closely, but I was definitely climbing faster after I got that).