Sewer line repairs… better to ask seller to repair or to ask for money back?

TLDR: Normally for any repair my preference would be to have seller do a credit or to renegotiate the price so I can get the work done myself but I know sewer repairs can get really expensive and it's kind of like opening a can of worms so I'm not sure if it's better to a.) ask to have it repaired or b.) ask for the money and make sure it gets done right.

My inspection found a crack near the outside clean out (close to the sidewalk), areas with "moderate-severe offset effects," and an area with root entry. Those findings are here.

Background: Buying a 100 year-old home with the original clay sewer pipe. That's normal here. A seller is never going to replace the line just bc it's the original clay service line.

My inspector identified the crack on the initial inspection plus a clog, lots of build up, and some tree roots.

I asked the seller to have the line jetted and inspected to ensure it's clear and contiguous with no breaks.

Seller's plumber came out, jetted the line, took care of most the roots, did a terrible scope, and called it good. I said that scope is not adequate, they agreed, redid the scope with the "good camera" but it's still not good quality and it's not the full length of the sewer line.

I asked to have my original inspector go out and reinspect (at my expense) and, unsurprisingly, the crack is still there.

I'm hesitant to ask the seller to get it repaired bc I do not trust the seller's plumber (they either lied and knew they weren't doing the whole line or do poor work and had no idea they weren't doing the whole line, either way, don't want them doing any of the work).

If I ask for a concession then there's a chance the work is much more than expected (there are about $5k-$8k in other repairs that were identified in the original inspection so that makes me a little nervous).

My inspector said it's probably about $4k in work but he's an inspector so that's his rough estimate but who knows.

My realtor mainly says to just do what I'm comfortable with but I'm not sure.

Seller is an older lady who has moved into assisted living and I feel like she kind of got taken advantage by the first plumber so I'm a little nervous about that happening again with another repair.