if house was built by direct labour, then there is no 'builder' as such, all different people did different jobs.
Solicitor wants an indemnity in case there are structural defects. That seems a reasonable requirement, lest the place fall down next week and you will be homeless and wondering who you can sue.
you could always have an engineer have a look over the place for structural defects, but you will not get anyone to sing up to confirming tha there are none and will be none as this is not possible to do.
Is it a dealbreaker? Well that is your own decision. I looked at a house in 1989 that I wanted. I offered the asking price on first viewing and this was acepted. engineer found faults with roof and walls, but today, house is still standing and current owners (regrettably not me) are very happy with the purchase.
I'm not much help either am I? You and only you can decide.