Or you could just be straight and say that
Salah is 28
Mane is 28
Firmino is 29
And that all three are on long term deals that don't expire until 2023.
Plus they have signed Jot who has just turned 24 and is under contract until 2025.
They clearly have weaknesses especially in midfield but trying to pretend their forwards are a weakness is a bit daft.
It's not sying they are weak. They are a very fine forward line. Salah is world class, Mane and Firmino are extremely good (probably the level below world class) but perfectly suited to the system they are playing in. However within a few months 2 will be 29 one will be 30. Players do tend to slow up, particularly in a team/league that relies on physicality and pace. You have seen this already with Firmino, who's output has started to radically decline, and many of them wanted him dropped earlier in the season.
You also factor in, come the summer they all have 2 years left. Thats tricky, for players you want tom keep it's the "sign or leave" phase, as we saw with Ross. In fairness to them, I do think that will slightly change, with older playerslosing inherent value, but it is still a challenge for them. So it's not saying they are rubbish,more that they are declining in ability and there are contractual pressures for them.
They could easily have all 3 signed on to long term deals by the summer and the question goes away- whether the answer is right to keep them all is another matter, but the question is resolved. However if not I suspect they probably move 1 on to keep the other two. Don't be surprised at all though, if one is moved on, one signs and the other choses to wind a contract down.
As for Jota, you are right that he has been a smart signing. Probably less upside than Werner if he is to get settled but a more solid pick. That being said, for all the hyperbole, for a lad they paid 45m for, I am doubtful he scores 10pl goals this season. We will obviously see, but that seems to be the minimum bar youd want from a forward signed for that money, and he could well fall short.