I agree it's odd, but I think the main units for most Warmaster armies have a pretty simple way of determining their stats, based on what is considered a 'standard' Warhammer configuration.
For example, Halberdiers are your generic unit- one attack per model, light armour becomes 3 attacks for a stand, 6+ save. High Elf spearmen have one attack per model, light armour and a shield- which becomes 3 attacks per stand and a 5+ save. Orcs have two hand weapons (2 attacks per model) and light armour, which becomes 4 attacks per stand and a 6+ save.
I've found that this view works for most units. It's only when a unit's natural abilities seriously break the mould that things get shaken up- such as how Chaos Warriors have hand weapons, heavy armour and shields- but they naturally have 2 attacks per model, so the stand still has 4 attacks. It's really only 'when does a unit gain an extra hit?' that throws me.
Part of the reason I liked M. B. Hildreth's original Call of the Hunt was that it added an extra use for the spell- it could be cast onto an engaged unit, giving +1A (per stand, I think). Since it can only be cast in the Wood Elf turn, that helps epitomise to me the Wood Elf motto: Hit first and hit hard.
I agree with Aldhick's opinion on the extra forest. The same issue used to be true in Warhammer- without the forest, Wood Elves were excessively squishy and could not stand up to anything heavy. With too much forest, the Wood Elves were untouchable, and games would often become very dull/frustrating for the opponent. As much as I like the idea of the rule, I think it needs to be toned down or dropped.
As something of a replacement, I think Treesinging could do with a boost- perhaps moving a forest 2D6cm? As it is, I would only ever bother to cast this spell if I had no other possible spell to cast. Elves can't afford to be too mage-heavy, so having a 50/50 chance per mage to give forests a slight wiggle every turn is very rarely worth it.