I like this wacky list. No idea if it's any good. Why the Namarti Thralls - what do they have Sylvaneth don't? I would have chosen the eels. You'll have to keep all your non sylvaneth away from your woods.
I was having a bash at a Heartwood 2000 list too. Impossible to get Alarielle in there (1980 gets you basic heartwood and Alarielle. No battleline!). Could manage it on a 2500, I think. Would be really nice if you could battleline Kurnoths for Heartwood.
Base tax of 200 for heartwood (80) and free spirits (120) then:
1970: Branchwraith (80), Branchwych (80), 30 Dryads (270), 12 Kurnoth Hunters (800), Spirit of Durthu (380), 2x5 Tree-Revenants (160)
1940: Branchwraith (80), 2x 20 Dryads (400), 12 Kurnoth Hunters (800), Spirit of Durthu (380), 5 Tree-Revenants (80)
Or, you could get rid of the branches (losing summoning) and go for 60 Dryads off the starting line.
1980: 3x20 Dryads (600), 12 Kurnoth Hunters (800), Spirit of Durthu (380)
2000: 2x30 Dryads (540), 12 Kurnoth Hunters (800), Spirit of Durthu (380), 5 Tree-Revenants (80)
However, I'm not sure the Heartwood bonus' are really giving much - Bravery +1 and a 1in3 chance of resurrecting a Dryad/Tree-Revenant unit. The revenants do die quickly, but those Dryads can hang around for quite a while and you need to wait until they are completely destroyed before resurrecting, which is probably fairly late in the game, especially with units of 30.
Wondering if just free spirits as you get the extra movement, but at 120 that's quite expensive. At least you only need 9 Kurnoths and could fit in Alarielle.