Because, apparently, someone in charge of this section, who is a rigid thinker, is sure that "flera" only equals "several", and saw in OED that several is specifically less than many. Yet, I have spoken both Swedish and English since I was two, and I agree with your translation. So does this wiktionary page: https://en.wiktionary.org/wiki/flera
flera generally translates either to "more" or "several", and we find that it's more confusing to a much larger number of people to accept them as synonyms. We distinguish between many / several and många / flera throughout the course. Making the distinction is far more common than not in both languages, but especially in Swedish, to the extent that most natives will consider flera as a synonym of många plain wrong.
Unlike in Hugo's rudely put assumption, it's not like we decide how things should be and never change them. Things like these are evaluated over and over again. Actually, there are some inconsistencies in the course because we used to treat them as synonyms but stopped doing so because it was detrimental to learners in general.
And in this specific case, it's not like only the OED uses the "more than two but fewer than many" definition. So do Cambridge, Merriam-Webster, and Random House. I didn't bother checking more. MW does list the "many" usage as "chiefly dialectal", which I think sums it up nicely.
Wiktionary is an amazing resource, but far from an absolute authority. In fact, its entries on flera are incorrect in both English and Swedish: flera in the sense of "many" is a pronoun, not an adjective (as claimed by the Swedish page), and not a determiner (as claimed by the English page). When Wiktionary contradicts multiple of the major established traditional dictionaries, I would use caution in adhering to their suggestions.
Thank you for explaining it to me.
Många hasn't come up yet, but google translate gives "fler" as "more" and "flera" as "several", so, with hindsight, confusing when "more" came up for "flera".
Swedish is still very new to me and I'm sure the way it works will become clearer with time.
I hear the difference, too, and very clearly at that, though to me the pronunciation in the plural sounds more like an "n". Like Elin.7-1, I heard this before in another example sentence with "brev". But I dimly remember that on that earlier example's talk page a native speaker stated that they could not hear the difference.
Thanks Magnus, did you hear the robot though, it really sounds like an M... so confusing.
Normally, plural = singular for ett-words where last letter is a consonant. More examples:
ett djur - två djur (animal)
ett hus - två hus (house)
For ett-words where last letter is a vowel, you normally add an n:
ett äpple - två äpplen (apple)
ett foto - två foton (photo)
Example of exceptions:
ett öga - två ögon (eye)
ett öra - två öron (ear)