As a Lissandra main myself (over 500 rankeds in 3 years, and that is a lot for me), i'd say no, do not touch her anymore.
Even if the buff revert is totally justified given the situation (Riot did it wrong with the overpowered Protobelt bullshit to first nerf her and then the item), the champ should not be touched ever again. I guarantee she's fine, she is and will always be balanced. Not hard to play, therefore good on average gameplay, but great if used well. That's the definition of what LoL champs should be. Even her "mediocre" passive that people so much talk about is in the end quite well in harmony with the entire kit and mana costs.
I will not discuss and analyze, but given the past fuck ups that the balance team has done, i dont want anything more. No buffs, no tweaks, nothing.
Keep Lissandra where she is. Sincerely, a dedicated player.