Band/Sill not bearing directly and has a gap

[jplay2519]

I have a project where the original structure is brick piers with brick foundation/skirting walls and they have some areas where the brick walls were replaced with CMU. the issue is that the sills (pressure treated) and bands (untreated) have a gap to the foundation walls below. I'm trying to determine a fix and each one I choose in my mind doesn't work.
Option #1: Grout the gap. Issues with this is that the untreated members can't be in contact with the grout.
Option #2: Provide foam to fill the gap. That doesn't really provide bearing does it? Just fills the gap but nothing structural.
Option #3: Make them build a wall inside that brick and have it go up to the joists, or have a post and beam system installed. Issue here is cost, they are going to go nuts if I say to do that. I've worked with these guys and they have suck framers so they always have issues and even when I give simple solutions they cry (posts installed without post bases so I recommend Simpsons only retrofit baseplate....oh my do we HAVE to use this, um yes if you want a connection to the foundation or you can take it out and put in a typical base) sorry, venting instead of sticking to the matter at hand.

I'm attaching photos too so maybe it can spark some ideas.

 

[structSU10]

Can you reliably slide a separation membrane - tar paper or the like - under the untreated lumber prior to grouting?

 

[jplay2519]

structSU10 - Yes they could, I didn't think about that at all. This is why I like to try and prod peoples minds.