This 14 day booking window shouldn't stop you at all... Just book J on your ideal route, and leave a 5-6h layover. Then within 2 weeks of departure pay the $90 chane fee to switch to F when possible. Repeat for the way back if it's more tha. 2 weeks from when you made your change. It's still totally doable. I just snagged round trip LH F (YUL-MUC in new F, MUC-JFK) for next week. Easy [edit] if you've already paid F miles for the trip and your flight in J shows some new F space the fee should even be waived!

As for some flights not showing up with AC but showing with ANA, all you have to do is call in and ask an agent to direct-sell the space. I've never been denied and it's always worked for me. I even had to direct-sell an AC flight one time

These are just a few new twists in our game nothing major. The LX F is a sad loss though.