And this one is a bit more charming. 

Many of the houses are so charming to me.

Working like a charm. - How about the ducting?

Efficiency is key, and that's where we're steering this ship.Your mention of the chicken and egg scenario had its charm, no doubt.

They've got charm, attractions, and might need a bit of tender love and care.

Repainted the walls etc with 'mold suppressive' paint & again upgraded the old exhaust fan.

We built our 16 person cabin with fire suppression in it because we didn't want to play games with the definition of bedrooms to skirt around the regulations.While I don't disagree with the point your making, I will say that our interactions with the fire marshals and city officials have been way better than we expected. 

It does seem that higher rates are reducing demand for loans, which is driving up home inventory which could - I stress could - suppress home price growth.

@John Morgan I had a really bad rehab that had the same issue and just rolled the dice and had the hardwood sanded/refinished and it worked like a charm.

Frankly you may have to decide between a) insulation value, b) historic charm or c) cost/budget..... you probably will not be able to get all three.....So first just be aware that this 'exciting' journey will be very costly (in my experience) so determine the project budget first and see how much your ROI will suffer (it will) and if that is worth it to you.