I think this all hinges on what it means to 'clear the finishing line and marks' as this is when a boat is no longer racing.  When has each of these boats 'cleared' the line (please assume the boats aren't all there at the same time!)?

The dictionary definition for clear is:
: unhampered by restriction or limitation: such as

d: free from obstruction
clear passage

f: free from entanglement or contact
staying clear of controversy
keep clear of the boundary

In the OP, the rules of Part 2 (in this case 10 and 23.1) will still apply throughout as I think there is no doubt that Red is still 'sailing in or near the racing area' and she has 'been racing'.  As Rob points out, the two-turn penalty is only available to boats that are racing and so the determination of whether or not she has 'cleared the finishing line' is the critical point.  If she has not cleared the line, then she breaks rule 10 and can take a two-turn penalty and finish a second time.  If she has cleared the line then she breaks rule 23.1 and her only option is to retire.

Using the last point of certainty principle, you would assume that she has not cleared the line until you are certain she has cleared the line.  In this case, I would fall on the side of 'has not cleared', that she breaks rule 10 and not rule 23.1, and take her finish as the one after she did the turns.

I am not sure that Case 148 is all that helpful here as it doesn't give any criteria for what it means to be 'clear of the finishing line'.

The notion of 'unfinishing' is very similar to the notion of 'unbreaking' rule 16 when a boat breaks rule 16 by altering course and not giving a boat the room to keep clear but then continuing to alter course to give that room.  It is the recognition that there is a time element to some of our rules.

If you go to the video - at 3:32, you can see the boom is on the centreline and the boat is head to wind (he even says the boat is "starting to tack") - SCULL 3; at 3:56-57, it's well past head to wind and he says, "Just pump the rudder once, twice, that's not really sculling" - SCULL 3; at 4:19, the boom has crossed the centreline and he's ducked to the far side of it, three pumps of the rudder with the first one crossing the centreline - SCULL 2, SCULL 3.

Slamming the board down doesn't stop the boat going past head to wind, it gives the directional stability to scull down to offset the backing and/or go backwards on a desired direction. 

Ben ... I think there is a new MR Call .. or maybe it was a Rapid Response .. where they discuss, in the context of RRS 16, the concept of a KC boat 'not being able to continue to keep-clear, if the KC was not keeping clear when RRS 16 initially applies.

The reason I bring this up in this context to possibly frame this in the context of RRS 16 and how Case 50 creates a reasonable timespan of action between RRS 16 and RRS 14.


From RRS 16's POV
Each time a ROW boat changes course, she shall give the KC boat room to KC.  When the KC boat is in an obvious state of KC'ing (let's say P/S .. > 6 BL's apart  ... bow-to-bow original course intersection), each time the ROW alters course, there is a reset opportunity for KC to 'continue to KC'.

From RRS 14's POV
A ROW boat need not act to avoid contact "until it is clear" that the KC is not keeping clear.  Rhetorically, RRS 14 a single moment in time at which time the ROW boat must act in the time-rhelm of "reasonable possibility".  At that point of time of action, the KC boat assumably is not in a state of keeping clear.  If ROW's action to avoid contact involves changing course,  that change of course doesn't effectively create new RRS 16 KC room entitlements to the KC boat. 

So, Case 50 spans the space between "Clearly KC'ing" .. where RRS 16 provides new room to KC with a course change by ROW .. and "Clearly NOT KC'ing" where the ROW boat's actions may be too late to avoid contact.  

I am a big believer in online official notice boards.
During covid, when we could sail, we did not want the crush of compeitors by a physical notice board.
We got used to the new systems, and began to prefer them.
It is ok saying the internet may go down, as an outsider at a club, geting access to a printer is difficultt at international wvents you canot bring your own printer, you cam only write so much in a given time.
I do events run from multiple cluds, a crew member had to be dispatched, to check for prptrsy scedule and si changes.
Now all are online generaly, and notifications are given by e mail.
In multi class regattas just posting all the protest time limits was a majour task, now managed from the pc.
Same for hearing schedules, not to aay the ease of the notices then a commirtee is protesting.
Lang live the electronic sysstems.
Do however specify the online system as the official notice board,.
Get the link from rrs post about the venus the qr codes.

And it did a superb event at the Fastnet Schools this weekend - well done!