I'd like to introduce this ridiculous belief, followed by last post.

Some people have toaught "manners" to young people incorrectly.

TNot only do they sometimes not only look arrogant but also fabricate new manners which we have never heard of and can't believe.

One of the beliefs they spread is that you should use "承知しました (Certainly.)"

It is confirmed that these phrase had been considered to bhave the same meanings and there isn't such a manner didn't exist until 2011.

Now that many people believe it.

The most ridiculous manner I think is that you shouldn't use spout when you pour a drink for older people because "縁を切る (cutting the edge)" means bad luck in Japanese.

I don't have any idea why spout is still exist withouts exist if not for pouring a drink.

Why do spouts even exists if you don't use it to pour drink.
This would be another ways to write this sentence.

I'd like to introduce a ridiculous belief, followed by the last post.

Some people have toaught "manners" to young people incorrectly.

They sometimes not only look arrogant but also fabricate new manners which we have never heard of and can't believe.

We call them ”失礼クリエイター (Rude creator)” sarcastically because they say "Something is rude, so you should..." a lot.

I think "rudeness creator" would make more sense, but I'm not completely sure as to whether or not that reflects the Japanese term.

One of the beliefs they spread is that you should use "承知しました" (Ccertainly.)")

instead of "了解しました" (Ccertainly.)")

It ishas been confirmed that these phrase had beens were considered to bhave the same meanings and that there iwasn't such a manner until 2011.

The pluperfect is used more if you're talking about something even further in the past than when your narration is set. Here, since the idea is simply that this idea didn't arise until 2011 (rather than, for instance, that in 2011, something else happened), it should be avoided.

Now that many people believe it.

The most ridiculous manner that I think of is that you shouldn't use the spout when you pour a drink for older people because "縁を切る (cutting the edge)" means bad luck in Japanese.

Or: "I think the most ridiculous manner is that…"

I don't have any idea why spout is still exist withoutif they are not for pouring a drinks.

manner teacher

What you have isn't incorrect. I would propose the change to etiquette teacher however. Etiquette is an obscure word, don't be worried if you don't know it!

I'd like to introduce a ridiculous belief, followed bing on from my last post.

They sometimes not only look arrogant but also fabricate new manners which we have never heard of and can't believe.

This is a bit of an awkward sentence

We call them ”失礼クリエイター (Rude creators)” sarcastically because they say "Ssomething is rude, so you should..." a lot.

One of the beliefs they spread is that you should use "承知しました (Certainly.)"

It ishas been confirmed that these phrase had been considered to be sameequivalent in meanings and there isn't such a mannerusage until 2011.

Now that many people believe it.

The most ridiculous manner I think is that you shouldn't use a spout when you pour a drink for older people because "縁を切る (cutting the edge)" means bad luck in Japanese.

I don't have any idea why spout is still exist withouif they cannot pouring a drink.