Whose standard ? The current WT rules. What else !!
But WT has many rules. We also have a rule saying to avoid changing LNAB unless we know what we are doing.
I am saying that I would not change the LNAB of a profile based solely on the spelling by one priest on one record, be it the baptism record. Especially if that spelling seems odd or exotic. (I could be the one misreading it, or relying on some bad Ancestry indexing). I would rather put it in OLN, put it verbatim (with reference) in the bio, even add a Needs_LNAB category, and leave it until we know more about that specific family (siblings baptisms, name at marriage of the father ... ). I like to see to evolution of names but I rarely consider a spelling error in one record as an interesting historic fact worth noting. And when I do, I put it in the Research Notes.
I am also saying that the "use the baptism record spelling at all cost" rule, as it is suggested/understood by some of us in Project Québecois, is sometime in contradiction with the WT rule that suggest : "unless there are other documents from at or near the time of birth that inform us about a more common or correct spelling." It is difficult to obey two masters. This could even lead to a LNAB feud on some profile : one person following the Project rule the other the WT rule.
And there is the problem of duplicates. The more exotic the spelling, ths less likely it will be found. WT was design for US, English speaking people, so it's Search is not particularly good with French or other languages.
Now, I understand your point about finding the parentage over frontier. But for me it is only a common beginner's mistake to rely on one spelling be it LNAB or standardized. Your example seems to make my point : Imagine if his baptism record has been Coetu. It would not have help you finding Cottu in France. The fact is : you cannot rely on only one spelling and the rules about LNAB have nothing to do with that. (CLN and OLN can help here too)
My conclusion about changing the LNAB: The spelling from one baptism record might be OK for a new profile but by itself it should not be enough to change a LNAB.