Well, as I have some time, here are my thoughts. Let's start with a quick analysis to sort all that.
Why was Carapace bad in MO but Shield Wall is over the top with NR?
First of all, SW is plain better with 3x boost2+shield compared with 2x boost3+ shield. Leader points get spread wider, loosing a buffed unit allong side just deletes 1/3 not 1/2 of Leader. And of course one shield more gives the option of using it on vulnerable but strong cards early on e.g. bronce engines.
Synergie and usage:
Nr has actual shield synergie but most is in the meme corner but still it is a valid faction mechanism while MO has no clue at all. More important and probably most important is the engine protection it offers. Nr has a whole lot of engines spread over all prov. slots providing great value along combos and synergies to even increase the value (e.g. drummer-tridam) but are vulnerable through low bodies.
MO does not offer these. MO engines are either well protected to begin with like Larvae, Beas or Phantom or they split to lower removal chance/value. The only engine fitting the spot that comes to my mind is Nekurat, a total tribe card that depend on its own bloody archetype. Or my WH boy (5p ping1 /dominance ping2, sorry forgot the name in all that Imlerith Ge'els swip swap wich allways has a big haircross above his head, wether beeing shielded or not.
High end Gold usage: MO had some ... well wishes to buff till dominance enabling some good golds like Adda or Eredin himself but nothing that can't be done even better with generic MO big boys.
NR loves its boost. Half of the top end has a nice Inspired bonus like baron, shani, Pris etc. And the biggest issue perhaps the interacion of shielded (and boosted) Duels. A single shield in a Duel could easily play for 5-10 points of removal and that is where the cieling has just lost its limit.
So as a conclusion: MO only added more value to opponent removal. MO biggest fear is not removal by midrange damage but tall removal - not fitting.
NR has a lot to protect and fears midrangy damage because it can lose most value if they don't stick. LOts of 4,5,6 p bodys with big potential.
Looking at my own thoughts I guess at first I suggest removing one charge. Make it an actual choice wether to use leader or not. We already seen the change to uprising by just losing one charge. (Not increasing the boost, 2 is enough)
At second I would test lowering the buff value even more. Compared to Inspired Zeal, I guess NR can value a single shield as much as a zeal, given the number of allready zealed options and other ways to stay until order's ready.
The idea of spawning Volunteers instead of boost sounds also reasonable to me but is a bit clunky at the same time. The combination of protection along swarm support - to be honest - I just can't really imagine it. Could be cool to protect your swarmers (fregates) while spawning more bodys and probably enable some "crew" but could also be very odd. This would surly move shield wall out of the "autochoise" spot it is right now.