[Galin]

The thing is, we know that T was willing on occasion to contradict published material, and then regularize the change in print: vide Finrod > Finarfin and Inglor > Finrod.

Okay, and what then is the truth according to canon (under my easy definition)?

Text was changed, no doubt, but at the moment I'm not certain that there is anything necessarily in conflict between the first and second editions here. Conflating editions one will find that there's a royal House of Finrod, and a royal House of Finarfin -- which could be references to the same house/clan, one being in a larger context perhaps. And we could say that Finrod Felagund was the son of an Elf named Finrod, thus making Galadriel Finrod's daughter as well, as she is noted as sister to Felagund [there's no Elf named Inglor unless one counts Gildor Inglorion of the House of Finrod].

Sure, when we know and plug in the posthumously published details here we have a very different answer, one according to what Tolkien "intended" (intended for a given time at least). Finrod Felagund did not have a father named Finrod (although it would be acceptable if he had), his father's name was really Finarfin. And when Tolkien made this change, he arguably should have been consistent with "House of Finarfin"... but here again, does anyone know Tolkien thought House of Finrod (Gildor again) was overly problematic where it appears? Did he miss it in revision? I would say probably, but it's not a great problem from my perspective, especially as Finrod came to Middle-earth, not Finarfin.

Due to posthumously published papers we know what went on behind the scenes here, but I propose that Tolkien would still (if given the chance) seek out an internal answer, even if it was as (arguably) "feeble", like a scribal error (of an internal character), of his error as "translator" (not author), and perhaps even a printer's error, considering these F-names and such. What's strange is, the only reason that I'm aware of for why Tolkien switched the name Finrod, did not, in the end matter (see WPP, PE17, though Finarfin became a Sindarization in any case, even though this Elf never went to Middle-earth). It was, arguably, an unnecessary change to an already published detail.

Anyway I doubt you will find anyone seriously contesting the "fact" that Galadriel and Finrod Felagund belonged to Nos Finarfin...

... not even me. Well not today... maybe

And anyone who cared nothing of the revisions, or any of the posthumously published stuff, would still likely choose [as internally "true"] the revised second edition over the first in this matter, assuming that a "correction" of some kind had been implemented... for some reason.