Does anyone know if the fluency percentage can continue rising, even after the level 25 ceiling has been passed? Many thanks
Not 'everyone' ignores the fluency percentage! However I would advise you not to take it too literally. It goes up to about 55 or 60% depending on which language you are studying. I think it's also easier to get the higher percentages on some platforms than others. If you've got to level 25 and your words are all pretty well strengthened then there probably isn't much more to gain.
Are you doing a reverse tree? They have some different vocabulary and more sentences to translate into your target language (rather than translating into English most of the time) so can be quite helpful to sharpen your skills. You should be able to whip through the earlier skills fairly easily. - Also most of the forum discussions are in the target language, which gives helpful practice in reading.
Just ignore the fluency percentage. Everyone does. Many people have complained about it on Duolingo. Here's an article that might interest you: https://www.duolingo.com/comment/9064816/Fluency-percentage-confusing-and-not-very-motivating . Good luck in your studies and I wish you well!