Does this need to be rebuilt?

[optimystery]

I decided to finally deal with some blown plaster around a kitchen window, and ended up removing all of the plaster below one of the windows, which came away easily.
Underneath, the brick seemed slightly damp, which is strange given all the hot weather we've had recently.
At either ends the wood below the sill is spongy and rotten, and the inside of the skirting is the same. The mortar between bricks was also very crumbly/dusty, and I've removed most of the looser sections.

Around 8 years ago my neighbours downstairs had an extension built, which includes a flat roof and parapet wall below my kitchen bay windows.
It seems to be running off correctly, but there may be a problem related to this. The builders identified a crack around my windows at the time, which they repaired, by the looks of it with concrete.

The double glazed windows are probably 25-30 years old, so I inspected them properly, and found a whole load of worrying problems, although no signs of blocked drainage or a failed inner seal.
On the outside I did find failed caulk, cracks in mortar, blown brick faces, what looks like it could be salt deposits, and worst of all, severely bowing walls.
Above these windows is a sloping roof. at some point in the building's history this and the upper main roof were replaced with concrete tiles.
There is also a slight bow on the outside wall along the side of the building, which a surveyor has looked at and said is not ideal but also not in need of a rebuild. I had leaks from under the top floor parapet wall, but that's a separate issue, and the completely redone flat roof up there seems to be ok.

To me this looks pretty bad, and possibly not fixable with re-rendering, but am I over-reacting?

A lot of photos I know, but I tried to document all the problems in a way that's clear to see.
I tried to upload these as an external gallery, but it seems I need to place all of them inline here!

The house is semi-detached, and there is a passageway along one side, which may contribute to subsidence. Also, heavy lorries hitting speed bumps cause massive vibration and shaking which could be damaging the foundations.

[optimystery]

The rest of the photos...

[aeromech3]

Not a rebuild in my DIY opinion, but you need to trace the source of the damp, it might be tracking under the flat roof covering and not necessarily where it meets your brickwork especially if the flat roof has several layers; your roof also needs a look at, as without a gutter the bricks below are suffering; a tidy to the brickwork mortar, even though they are hard baked bricks the mortar also appears a strong mix and hence more likely to have cracking; some bricks have blown faces, but not serious considering the age of the property and lack of gutters, perhaps a paint on, clear, water sealer for them.

[wine~o]

I would deffo get someone to have a look, there are obv. signs of previous " remedial work" which looks like a strong mortar mix used.