Yes.
Who knows how much time has passed between each event, and every single time that group's actions was cataclysmic. I don't care enough to start numbering them all, but it's particularly egregious when a human(?) witch dominates an entire country of elves, and then eradicates an entire army of beastmen. Surely there are spies of very powerful individuals strewn about, and at this point, surely enough time has passed for this critical info to establish itself: There's a group of humans that are more powerful than anything they've ever seen before.
Combine that with the MC's "Clown" getup, i.e: his 3-men coverup party (knight, assassin and himself) -- and they obviously made a name for themselves. People can piece together enough to pay more attention to them, for the very least.
That being said, it's not like anyone can point at the MC's face and go: "It's him, watch out!" -- sure, but for the very least, anyone with an information network should know to be even a little bit wary, if they ever come across a group of humans that don't immediately shit themselves on the sign of conflict.
I'm not sure you can claim to be operating on facts and logic when you immediately begin by making assumptions that are not based on any verifiable fact other than you feel it should be so.
Lets talk facts. We do not see extensive intelligence networks belonging to the non-human races in the manga story. Those guys behind the Beastmen have one, but literally said they haven't shared what little intel they have with the other remaining nations, so that's all there is. You could criticize the author for something you may consider unrealistic, but historically it has happened and especially so with cloistered and isolated states. We don't need to assume if it's the case here,
we don't see any such thing. If you're going to argue with 'facts', how about starting with facts?
If that's not enough and you insist there's no way the setting can follow any other premise, there's countless classic examples of such things in history. We don't even have to dig very far down the list of famous downfalls....both Western and Eastern Roman empires, among the largest states of their time, fell with much of the rest of the world not realizing, sometimes for years. Including their neighbors, vassals and subject lands. There's so many reasons why, not least of which communication relies on infrastructure, which tends to collapse when a nation falls. So even your 'constructed' fact doesn't appear to have much merit. We don't have to talk about whether it's likely, only plausible. Because such unlikely but plausible scenarios have happened in history...prominently, I might add.
That's my long-winded way of saying you're literally ignoring the facts that are plain on the manga pages themselves for no good reason.
And aren't you only covering half the scenario? We do see Light engaging in considerable efforts at counter-intelligence, which you have completely disregarded mentioning.
None of this is happening in a vacuum. Efforts to hide and compartmentalize information can be very effective, and in medieval settings, can even hide details about whole countries. He has legions of loyal followers, including animals, and we also see, plainly, that he carefully prepares the 'stage' every time he appears in public. If you wanted to make educated guesses, you would begin here, which would have led you to at least speculate he tightly controls the flow and form of information that is spread regarding his group.
The 'Witch' is a front, and one which is grounded on the basis of her being a dragon tamer. 'Dark' has fewer accomplishments than you think he does. For example, nobody even knows what happened in the Dark Elf dungeon, it simply collapsed and they were the only ones to live is the only concrete information available, and that's all he wants anyone else to know. Chaos has also been introduced as a potential body double so that 'Dark' doesn't have to be associated with Light in the future and even an association with the "Witch", if it were ever found out, can still be a useful misdirection tool. This whole arc is about the secret taskmasters of the Beastmen
not having enough information except what Light wants them to know, and everyone else having almost none.
Again, what facts are you and Grailm talking about? Maybe you should care more and start numbering the group's 'actions', and maybe you'll realize you're not standing on much of a leg there. Word is getting out about the "Witch", not some grubby human who got lucky a few times, who Light is deliberately spreading misinformation about, and who one day can simply disappear...because he doesn't really exist.