Caveat: English is not my native language

Angelo, for me "each" referes not to incidents but to the two actions "hail" and "display red flag". So a boat is obliged to do each at the respective first reasonable opportunity. 

For what it's worth I asked Google's opinion on that matter. I think it kind of backed my understanding (emphasis by Google):

"In this sentence, the word "each" refers to the two required actions: hailing "Protest" and conspicuously displaying a red flag.

Grammatical Breakdown

The phrasing is taken directly from Rule 61.1(a) [sic!] of the World Sailing Racing Rules of Sailing. The phrase "at the first reasonable opportunity for each" means:
- The boat must hail "Protest" at the first reasonable opportunity for hailing.

- The boat must display the red flag at the first reasonable opportunity for displaying the flag.

The rule recognizes that a crew might be able to do one action before the other. For example, a solo sailor can instantly shout "Protest" during a collision, but they may need to untangle lines or stabilize the boat for a few moments before they can physically reach and hoist the red flag. Under this rule, the timeline for evaluating a "reasonable opportunity" is judged independently for each action.

Mark covers the case law, and there are probably others. I don't think there's any doubt about the meaning of the rule.

However I think its a bad rule. To follow up on Richard's last sentence,  I'm not aware of many jurisdictions where a failure to shout "Stop Thief" after being robbed means that a subsequent prosecution is inevitably abandoned.

If I may, I'll start with the easier issue - rule 11.

I admit it took me time to link 'need to take avoiding action' with this scenario, until I widened my view of what 'need to take avoiding action' is.  We are so conditioned to think that 'avoiding action' is only a course change.  It's more than that.  Now, the more I look at this, I'm satisfied with rule 11 breach.

Did W break RRS11? Yes; without a doubt.

Any continuous restriction on how RoW can sail is the same as saying RoW has the need to continuously take avoiding action.

All the while W is in that close proximity, L is restricted on how she may trim her sails.

The 'avoiding action' referred to in def. of KC  is not always a course change.  It may be sail trim, crew weight positioning, hailing (Case 107) or many other 'actions'.  In this case for example, L's avoiding action is her need to keep her sails trimmed or only trim them slowly.  That's what's required to avoid contact.

L, sailing so close so as to restrict how W may trim her sails breaks rule 11.

I am happy with rule 11.

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Now to the tough question - rule 14 - what is 'caused and reasonable'.

How does fully releasing the sheet with the knowledge of the result in close quarters fall within the range of ***reasonable*** sailing, whether intentional or not?

This is where we are getting stuck.  Specifically,  that word 'caused'.   We've discussed this word before. (About every 12 months it seems).

That word has a broad range of use, doesn't it?

For any incident there may be a number of contributory factors, and these are often referred to as causes.  Ok, but if we can find a cause to a cause, it is not a root cause.  There is usually only one/a few 'root causes'.

A root cause is the fundamental, deepest underlying reason for an issue or event.

Rule 14 must require us to drill down to the deepest level of cause we can find which also has a binding rule which goes with it.  Otherwise we are left with a bunch of 'causes' with no real endpoint to address or fix.

RCA#1.
Rigs collided.  Why?
1.  L stood upright.  Why?
2.  L's mainsheet was not taut.  Why?
3.  Mistake/Poor Sailing/Broken equipment etc... Why?
Root Cause: Bad luck/Training/Poor maintenance/etc

Dropping mainsheet is not a root cause.  Additionally, there is not a rule prohibiting bad luck/poor training/poor maintenance.  (Don't say r14 - circular reference!).  It would be ridiculous for the rules to forbid mistake or bad luck.  Imagine this...

Rule 9 ¾ - Bad Luck and Mistakes - A right of way boat shall not have bad luck or make mistakes!

No.  These issues are considered to occur within reason in sailing (not reasonably possible to avoid).  They are going to happen.  They are accounted for in the rules and the interpretations (seamanlike definition, 'reasonable' in rule 14.).

Within rule 14 reference frame then by dropping the sheet, L did not break rule 14.

RCA#2.
Rigs collided.  Why?
1.  L stood upright.  Why?
2.  L' s trim change was sudden and W did not have time to react.  Why?
Root cause:  Distance between the boats was insufficient for reaction time.

Distance between boats is a root cause.  Additionally, there is a rule which requires that the distance between the boats be sufficient to allow RoW freedom of trim, which must take into account reaction time.  It was reasonably possible for W to increase the distance.

Within the rule 14 reference frame then, W broke r14.

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That's my progression through this.  It may be wrong.  (I have been wrong many times before!)

It may be that in practice at a real event (in absence of any official directive) JohnS's reasoning would be preferred.  I'm ok with that.  I understand his reasoning.  It's not uncommon that there are different interpretations to rules.  In absence of authoritive direction (casebook/rule change), either may be applied according to the majority of the jury.  That's why we have committees, right? 

I have nothing really more to say.

Thank you Paul for the change. And thank you all for the helpful suggestions.

We have had this come up a few times at our club and have defined the winner of the trophy/prize/money as the person who entered the boat and paid the entry fee.

It is a good idea to set this out in NOR so that it is clear, especially when there is a large sum of money riding on the prize.