Shell Programming and Scripting

By design. Based on OP example and words; not based on your hypothetical input.
You should start a new thread if you would like me to provide a solution for you, addressing your input.

It is my belief that the original request was to change semicolon delimiters inside double-quoted strings to vertical bar delimiters. But, the given examples did not include a case where more than on delimiter appeared inside double quotes. Therefore, the original request is not as clear as I would like.

I did not ask you to make any changes.

I see no reason to start a new thread when pointing out to the original poster that the code suggested by you, the code suggested by greet_sed, and the code suggested by me (and refined to a better suggestion by RudiC) do three different things if there is more than one semicolon inside double quotes: Your suggestion changes the 1st semicolon, greet_sed's suggestion doesn't change anything, and my and RudiC's suggestion changes every semicolon.

I believe it is entirely up to bartleby to determine if any of this matters in the real input he/she will be processing (instead of the contrived 2-line sample input) and, if it does matter, to choose the suggestion that behaves the way bartleby wants it to behave. But, I believe that bartleby should be made aware in this thread that the three suggestions do not do the same thing and should be warned to determine whether the differences in our solutions matter.

I do not doubt in your belief. However, by your own words, your belief made you assume with what you were not clear about, to start with.
I chose to interpret the request as stated:
One semicolon. Single semicolon reference, in both instances, highlighted in red, follow by specific post:
It was clear to me as stated. My solution was designed based on the given example, not based on requirements conceived by me. Perhaps, it would had been more understandable if you were to ask for direct clarification to the OP, excluding other suggestions not given by you. Instead of giving an audit of other suggestions, based on your assumptions and leaving there to anyone to interpret.

Not quite accurate neither. You are still declaring it based on your belief.
My suggestion will replace any semicolon which precedes another semicolon, followed by a literal double quotes, followed by one or more alpha-numberic characters. Which will be applicable to the shown example and it will not provide the expected results if the shown examples are not representative. If that's the case, the OP will communicate back if he or she is interested on the suggestion.