The Leica 135mm makes for a nice 205mm on the Fuji. Failing that, yes - an R lens with appropriate adapter would work also. FWIW, the 55-200mm zoom is relatively cheap (cheaper than an R lens and adapter) and might be the way to go; bonus is AF and OIS.
The "compatibility list" for the Fuji M Mount Adapter is accurate - but misleading. It's not that the lens is incompatible with the camera... It's incompatible with the
adapter. The issue is that the Fuji adapter has a really neat function button which brings up the lens focal length settings (and corrections). If you change lenses often, this is a very nice feature, as otherwise the settings are down in the menus. I hope Fuji allows us to assign this to a normal function button with a firmware update! But anyway, the reason for the incompatibility is this feature requires electrical contacts between the adapter and body and this narrows the throat (and depth available) within - and some lenses are just too fat or too deep to work with it.
The workaround is a Metabones, Novoflex or other adapter that lacks these contacts. I'm tempted to pick one up JUST for the CV 35mm f/1.2 Nokton. But like I said, you'll be setting the focal length in the menus with these...
UPDATE: I updated ACR from 7.1 to 8.4 (for CS6) and this made a world of difference. For one, no more DNG Convertor to go from RAF->DNG. Bridge/Photoshop now groks the RAF files directly. Furthermore, the Fuji film simulations are available as a drop-down (yay!). And, I do believe the resulting images are a bit sharper. I'm currently going back to previously processed files and comparing... FWIW, LR 5.4 can do this as it seems to have a separate ACR. But I'm a Bridge/Photoshop kinda guy.