Not entirely. The walls, structurally, were OK.
The roof had been practically destroyed by lead thieves and had massive holes in it. Firstly an emergency cover had to be erected to allow the building to dry. That took cranes and scaffolds and safety lines and heaters and dehumidifiers. The roof was then rebuilt to modern standards, using modern replacement materials that met with the approval of the local authority, the architects and the listing requirements, a lead replacement substance had to be found, approved and installed ( so the scum don't come back) it was insulated and the support timbers replaced where required. A couple needed to be replaced with steel due to the fact they were not suitable for modern structural support requirements and then hiden so they didn't stand out. Asbestos was removed. Accessing the roof required modern scaffold and safety equipment, welfare facilities, lifting equipment, lighting, safety lines etc etc.
The internal walls had to be stripped back to bare stone. That meant hacking off layers and layers of ancient painted plaster which uncovered more asbestos fibres, lead, arsenic and all kinds of nasties. That all had to go. Safely. That all still has to be replaced and will be a massive job requiring expensive heritage craftsmen who will restore the painted plasterwork to "as new" but using modern techniques and materials. Also many of the busts and ceiling roses have been damaged or broken beyond repair. They have to be replaced. They will not be molded in plaster and wire as they were but will be 3d printed. They will have to be affixed using modern scaffold and height access systems though.
While all this was going on the entire electrical system had to be stripped out and replaced because it got soaked and was not up to modern standards and while it would have been fine if the roof hadn't been removed by scum bags it wasn't for a restored building. The same was true with the gas system and the plumbing. It all had to come out and be replaced to meet modern standards. Mind you lead pipes are worth a fair bit for scrap which all helped the budget
At the same time better security systems had to be installed inside the building, on the roof and in the grounds as part of the insurance work. That all needed to be fed with power and data and several items "hidden" in the fabric of the building meaning more work and more interaction with the listing officers.
Oh, also the floor was rotten in places because the water got in and damaged the flooring and the joists. They all had to be replaced to meet modern standards AND preserve the respect of the remains in the crypt.
So no we didn't have to rebuild the walls. We did/will have to rebuild/repair almost everything else. It might LOOK the same in the end but it isnt the same as it was nor was it rebuilt using the same standards and equipment used in the 18th century. I bet it needed fewer men and was cheaper back then to.
PS it isnt finished yet either.
PPS Not even looked at the organ yet. Christ knows what that will need.
write to them and ask them yourself. I doubt, however, the answer would suit your needs.