I tried the Moonstone (from
https://www.mobileread.com/forums/showthread.php?t=97437) and the TOC links work fine on my 650.
I have found links in general to be a bit fiddly on the 650 though - if I press them for too long they highlight rather than activating the link. I've adjusted to tapping them quickly and lightly, and my fingertip is usually not accurate enough: it's easier with the stylus than by fingertip.