I would not expect an overhaul anytime soon for Sylvaneth. Their current battletome is in an excellent place as they are one of the most well rounded and balanced armies. As I see it, they are the first army (chronologically speaking) that ushered in the new power level of armies and as such have remained relevant. Sure, they're starting to slide a little but as a Beastclaw Raiders player Sylvaneth gives me nothing to complain about.
Totally agree with you Alexxk, I think Alarielle is in an incredible spot right now for her cost. Improving her casting with modifiers would put her over the top. In terms of her lore and place in the universe she should be a stronger caster but for her points I think it's too much to ask. Also, agree that 3 casting and unbinds is fantastic even with modifiers.