Does this mean that I only need to build two (2) more of each ensemble, for a total of three (3) each?
To upgrade to lvl 2 you need to build one of each ensemble, so three total.
To upgrade to lvl 3 you need to
add two of each ensemble to the ones you already have ‘in use’, so you’ll have three of each, nine total.
To upgrade to level 4 you need to
add three of each ensemble to the ones you already have ‘in use’, so you’ll have six of each, eighteen total.
Also, if you have the Vortex of Storage at a decent level you should be able to skip upgrading to lvl 4, which saves space as you will then only need space for max nine ensembles instead of eighteen.
This will allow you to complete the research tree for this chapter but will mean you will get stuck on story quest 76, which requires you to upgrade the Harmony Grove to lvl 4. But, if you don’t mind doing that, you can skip mandatory story quests once you have unlocked the first research of chapter 21. (Btw there is no quest to sell a lvl 4, just to sell
the harmony grove).