Mould Removal After Leak

Hello, I unfortunately discovered a leak behind the sink in one of my bathrooms the other day. The water has had time to soak the floor where it couldn't be seen and also flow to an adjacent bedroom under an interior wall. Black mould has grown on the floor of both rooms up to a couple of feet from where the leak occurred. I'm now letting the floorboards dry out and have had a go at removing the mould using bleach, vinegar and a mould remover product. However, I've managed to get rid of half of it at best so far, and the black stain seems to go beneath the surface of the wooden boards (which look to be made of chipboard, and they still seem structurally strong). Additionally, the mould in the bathroom is in difficult-to-reach places - inside a wooden enclosure for the pipes behind the sink and between the bathtub and the wall. I think removing it fully will require taking all of this apart. I'm not confident with plumbing, though, so I'd probably hire someone to do that, and I may need to hire someone else to get rid of the mould.

I was wondering how necessary is it to remove all of the mould, possibly at large expense? Would it be sufficient to dry out the affected areas so that the mould would become inactive? We only use the bathroom in question for toileting and using the sink, so it doesn't get very humid and has never required any effort to keep mould at bay before.

Also, should I be concerned about the wall between the bathroom and bedroom? I can see signs of water ingress reaching just above the skirting board in the bedroom.

Thanks very much for any help you can give.