Well, the term "rating limitations" isn't actually defined, so the normal rules of English should apply, and the requirement for these endorsements is surely a limitation on the SEL rating, wouldn't you say?
Nope. If I were starting from scratch with the regulatory language, I would say that just as "ratings" are things that appear under "ratings" on the back of a pilot certificate, "limitations" on ratings are things that appear under "limitations" on the back of a pilot certificate. "Passenger Carrying Is Prohibited" and "Limited To Center Thrust" are ratings limitations, not things that don't appear anywhere.
The FAQs have stated that these endorsements aren't required for checkrides, which suggests that it is/was their understanding is that these *are* rating limitation.
OTOH, the FAQ also saids:
QUESTION: §61.31(k)(2) says "The rating limitations of this section do not apply to . . . "
What about the additional training requirements of §61.31 for complex airplanes [i.e., §#61.31(e)]? high performance airplanes [i.e., §61.31(f)]? pressurized aircraft capable of operating at high altitudes [i.e., §61.31(g)]? type specific training [i.e., §#61.31(h)]? tail wheel airplanes [i.e., §61.31(i)]? gliders [i.e., §61.31(j)]? I read it to say that the paragraphs referring to category, class, and type rating limitations do not apply, but the paragraphs referring to additional training requirements do apply. For example, the additional training required to operate a tail-wheel airplane that holds an experimental airworthiness certificate. The pilot is Airplane Single Engine Land rated, but is not tail-wheel endorsed. Must a pilot who does not have a tailwheel airplane endorsement and who wants to act as a PIC of a tailwheel airplanes that holds an experimental airworthiness certificate is he required to comply with the additional training and endorsement requirements of §61.31(i)?
ANSWER: Ref. §61.31(k)(2); The additional training requirements specified in §61.31 are required to be complied with. The exception language specified in §61.31(k)(2) addresses the “ . . . rating limitations of this section do not apply . . .” emphasis added: “rating limitations.” The rule only excepts the “rating limitations” of this section, not the additional training requirements of §61.31.
Therefore, if a person does not have a logbook endorsement to operate a tailwheel airplane, or who has not met the requirements of §61.31(i)(2) [i.e., previous logged PIC time in a tailwheel airplane prior to April 15, 1991], then that person may not act as pilot in command of a tailwheel airplane regardless of the kind of airworthiness certificate that has been issued to the airplane.
(my emphasis added)
...which suggests that it is/was their understanding is that these *are not* rating limitation.