Is this junction box installation acceptable?

Is there a lid that you have removed to take the picture ?  the terminals should not be accessible without the use of tools so it needs a lid.

Are the cables likely to be pulled ?- presumably not if they are part of a fixed installation but if they are they should be clipped somewhere - that could be to the joist in the space above.

There may be questions about cable ratings and grouping factors, but it is stripped back to singles that are well spaced, so that has presumably been considered but worth noting.

Something like this - a DIN box and a row of terminals, is what often happens when a consumer unit has to be relocated and every circuit needs to be a few metres longer.

In ideal land,  might have liked to see some glanding or cable grip at the top of the box where the cables exit but with the lid on it could be a lot worse - you could have found those terminal blocks just flapping in the breeze in the floor-ceiling void.

The hole in the box seems to have been chewed out, rather than neatly cut, and the use of spray foam is a bit 'rough'. but that is not a breach of regs.

The terminals are full insulated so as long as the wires are fully seated, i.e. no copper showing, the hole in the outer box on its own is not a safety concern, as even if you could poke a finger in there is nothing for it to  hit that is live - so it meets IPXXB (jointed fingers) and  IPXXD (1mm spike probe) as well. That is before you add the floor above, that I presume needs tools to remove?

Is there some specific aspect that especially concerns you?

regards

Mike.

Presumably the cables were too short, or whatever was origianlly there has been moved? Its looks a decent enough install to me, far better than all the cables twisted togther in a standard box.