I love, love, love "New Frontier" and, when Arex and M'Ress were added to the zany mix in "Cold Wars", I couldn't believe my luck.
"Stone and Anvil" was, indeed the high point for the series. I hated losing Janos in the ongoing narrative, but what a triumph of an ending!
For me the ho hum bit was Selar's son. Disappointingly, he was drawn resembling an adult full-Vulcan in the comics (I'd imagined him a little more exotic), but I hated the hyper aging trope, which we'd already witnessed with Alexander, Naomi - and even fully-human Molly!
I didn't mind the time jump, but agree not enough was made of the drastic changes. The Robin Lefler storyline just got wilder and wilder, esp. with Si Cwan's death. Sadly, the finale of the story arc with Robin's immortal mother had already been done
in "Dreadstar", a Peter David-written comic I used to follow. (Ironically, I started reading "Dreadstar" only because when the Star Trek Office demanded that PAD remove Arex and M'Ress
from Issue #1 of his Series II "Star Trek" comic for DC, and replace them with Fouton and M'yra, good ol' M'Ress was reborn as a felinoid alien called Cookie in "Dreadstar".)
I also wish Selar's backstory had embraced the inclusion of the blind Andorian girl she adopted in the AC Crispin TNG novel, "The Eyes of the Beholders". That was an intriguing development left abandoned.