Simple suggestion

As you know when analysing a game with the computer analysis tool, if a checkmate sequence is detected the comment "Checkmate is now unavoidable" is displayed.
Well the wording is not totally exact because if the player makes a blunder then the forcing sequence of move will be lost.
I think something more accurate would be "Black/White stepped into a forced checkmate in X moves" and if the player blunder his advantage away you can add the mention "Mating sequence lost"

What do you think?

It means that checkmate cannot be avoided by the player who will be checkmated - the player making a mistake by not following the sequence is not "avoiding" the sequence.

But checkmate can be "AVOIDED" if the player with the mating sequence makes a blunder.
The word avoidance has a sense of inevitability, and like I just explained, this is not the case.

I mean the word unavoidable has a sense of inevitability :) sorry about that.

The engine always assumes best play. Therefore, I believe the current wording is consistent with the user's ontological understanding of the analysis procedure.

^agreed

Agree with #2, #5, and #6.

Could you create a "match" option
I want invite someone for playing e.g. 10 games
withdraw cost rating lost for all withdraw games

Players would have guarantee that can play 5,8 or 10 games in a row with the same opponent

Say what you want, the term unavoidable is incorrect because every so often the player will miss the mating sequence.