While I agree with almost all your points and think PLD is fine, Hallowed/Bolide's "true" immunity is quickly becoming more obsolete as time goes on; the devs have been making more mechanics simply apply debuffs even with 0 damage/invuln. taking P4s for example, invulning a botched rot pass still gives you the damage down, even with true immunity. Hallowed offers no advantage against the Phase 1 tankbuster or phase 2 double buster that the other non true immunities can't do. In fact, Holmgang has a massive advantage in both halves of P4 in being able to immunity the 1st & last tank busters in Phase 1, and both double busters in Phase 2. While I would concede Hallowed is nice for Heart Stake, a DRK can make that TB a joke without their immunity even when taking both hits with aggro manipulation, so I wouldn't exactly give that too many points in hallowed's favor.
Even in DSR, if you immunity the 2nd Heavenly heel in P5, it doesn't block the slashing resistance down with true immunity, meaning you can still get splatted by the last auto of the phase if the invuln was badly timed.
Both Zodiark & the current EX also don't care about true immunity, and will apply their 'this debuff makes autos unlivable' status to you regardless on their TB's. Fight design as a whole has been shifting to take into account cheese methods. Even the unreal trial got changed so death doesn't purge your force against might/nature debuff anymore. While any immunity is a powerful tool, Hallowed's power has been getting weaker over time compared to the other 3. Living Dead's recent buff makes it straight up stronger than Hallowed in basically every situation except extremely niche cases, and also gets a -2min recast timer which can be immensely critical to certain strats (like Holm enjoying soul tether -> HH#1 -> Cauterize -> Ahk 3 in DSR, something not possible with other immunities)
With fight design shifting to not care about true immunity and the huge amount of self heals/healer OGCDs these days to cover basically any problems associated with the other 3, Hallowed's 7min CD is quickly making it the worse immunity in terms of effectiveness. Still a strong CD, but the others are just plain better almost entirely because of their lesser CDs.