user29967: I just wanted to clarify the following incident:
When touching a piece without expressing the intend to adjust its position (cf. 4.2.1 FIDE Laws of Chess), such that it has to be moved because there is at least one legal move with this piece (cf. 4.3.1), one moves another piece (in an otherwise legal way), presses the clock, and the arbiter observes this; how should the arbiter decide?
Clearly, the move must be taken back and the clocks adjusted, but does this count as if an illegal move also?
In my opinion, this is the case, but the (possible) reasonings I came up with had some holes:

A player must make a move every time it is their turn, and press the clock if their move didn't end the game. Failing to move a piece is as if an illegal move (cf. 7.5.3). The player must move the first touched piece, but failed to do so; the move of the other piece is irrelevant (?).
A player must move the first touched piece, but moved a second one; two moves consecutively is not allowed (cf. 1.2). Violating this is as if an illegal move (?).

I'm happy for any definitive take on that, preferably with an official source backing it up.

user4418: 
Clearly, the move must be taken back and the clocks adjusted, does this count as if an illegal move also?

No. There was one illegal move. That move was punished as an illegal move. That move was retracted, i.e. unmade. A legal move was made. A total of one  move was made and then the clock was pressed.

The player must move the first touched piece, but failed to do so; the move of the other piece is irrelevant

Where do you get the nonsensical idea that the legal move is irrelevant?

A player must move the first touched piece, but moved a second one; two moves consecutively is not allowed (cf. 1.2).

Two consecutive moves were NOT made! One illegal move was made. That move was retracted and then one legal move was made.
Look, if I make an illegal move (my hand leaves the piece), say I move another piece when I am in check and that piece can't prevent the check by capture or blocking. Then I notice that my move is illegal or my opponent tells me before I have pressed the clock then I am perfectly entitled to retract that illegal move and make another legal move in its place all without penalty. Furthermore I am REQUIRED by the laws so to do.

29967: <p>I just wanted to clarify the following incident:</p>
<p>When touching a piece without expressing the intend to adjust its position (cf. 4.2.1 <a href="https://old.fide.com/fide/handbook.html?id=208&amp;view=article" rel="nofollow noreferrer">FIDE Laws of Chess</a>), such that it has to be moved because there is at least one legal move with this piece (cf. 4.3.1), one moves another piece (in an otherwise legal way), presses the clock, and the arbiter observes this; how should the arbiter decide?</p>
<p>Clearly, the move must be taken back and the clocks adjusted, but does this count as if an illegal move also?
In my opinion, this is the case, but the (possible) reasonings I came up with had some holes:</p>
<ul>
<li>A player must make a move every time it is their turn, and press the clock if their move didn't end the game. Failing to move a piece is as if an illegal move (cf. 7.5.3). The player must move the first touched piece, but failed to do so; the move of the other piece is irrelevant (?).</li>
<li>A player must move the first touched piece, but moved a second one; two moves consecutively is not allowed (cf. 1.2). Violating this is as if an illegal move (?).</li>
</ul>
<p>I'm happy for any definitive take on that, preferably with an official source backing it up.</p>
 4418: <blockquote>
<p>Clearly, the move must be taken back and the clocks adjusted, does this count as if an illegal move also?</p>
</blockquote>
<p>No. There was one illegal move. That move was punished as an illegal move. That move was retracted, i.e. unmade. A legal move was made. A total of one  move was made and then the clock was pressed.</p>
<blockquote>
<p>The player must move the first touched piece, but failed to do so; the move of the other piece is irrelevant</p>
</blockquote>
<p>Where do you get the nonsensical idea that the legal move is irrelevant?</p>
<blockquote>
<p>A player must move the first touched piece, but moved a second one; two moves consecutively is not allowed (cf. 1.2).</p>
</blockquote>
<p>Two consecutive moves were NOT made! One illegal move was made. That move was retracted and then one legal move was made.</p>
<p>Look, if I make an illegal move (my hand leaves the piece), say I move another piece when I am in check and that piece can't prevent the check by capture or blocking. Then I notice that my move is illegal or my opponent tells me before I have pressed the clock then I am perfectly entitled to retract that illegal move and make another legal move in its place all without penalty. Furthermore I am REQUIRED by the laws so to do.</p>
