That whole area needed to be jacked up the level. I have no dea what is under there in the crawl space sometimes old house have surprises. We had a 1905 house that had a basement put in in 1946 and the work they did was iffy at best we had to have the whole center of the hous ejacked up to level that was done over the course of about 3 weeks gently to keep from cracking all the plaster and lath it worked really well and we had a nice solid level floor.

You may be able to raise that section of floor without too much trouble. You can't be too fussy with 100-year-old homes.

We don't know what the root cause of settling is but it was either missed or ignored first time then this happened. I'd say it's time to address the cause once and for all and that requires going underneath with new wood and possibly support beam(s) and/or pier(s). BTW I've heard of pouring lite weight concrete over slab on grade but never wood with crawl space below. Are you using handymen or foundation contractors?

I know what is under there but locating exactly where this dip is from underneath will be tricky. The floor is glued down so not sure how successful the repair from below would be. Maybe he can work it loose and inject resin to keep it up?

I bought the place as a sagging fixer years ago. I bought three 50 ton bottle jacks off craigslist and with a giant wooden beam I jacked up the one corner with my friend. I think we raised it about 1.5 inches and then rebuilt the termite damaged foundation. It was a little scary so we didn't go all the way up. We did it in 48 hours... It never occurred to me to raise it over several weeks. I think it would have been the way to go. This was 2010 so no youtube videos on the subject yet!

@Klem1 Its lightweight leveling cement routinely used to level floors directly over the wood sub-flooring.

Whether I would redo it would depend on my budget and how long i think I will live there. I've jacked my floors and shimmed my joists and sistered others and it's still not completely level. That's just the way it is with old houses.

@HU-655806221 The thing is I have someone to blame and make them fix it but it will delay me moving back in, I'd need to wait for another 2 boxes of wood and then it might come from another lot and that may have color variation.

You have someone to blame alright ,your self. As you've found out watching utube isn't a substitute for training and experience.

Ok klem go to bed.

As above, and I'd leave it and move in. Even NEW build is rarely 100% perfection and don't ask me how I know this. : (

Mqybe you can just jack that spot a little more?

Maybe just jack that spot a little more?