> Tags can only be added by advanced contributors.

That's true, but it's not hard for someone to become an advanced contributor:
https://en.wiki.tatoeba.org/art...-contributors#

> And comments show up in everyone's feed, so posting a large number of comments is probably not very nice.

I've never heard anyone complain about the volume of comments at Tatoeba, and I can't imagine Nuel would be changing the volume significantly.

> What happens if one just disowns the translations they are not confident about?

I'm not a fan of the unadoption of sentences in any great number, since it buries the name of the owner, which is important information.

> Do native speakers pick them up?

Take a look at the 47,546 unowned sentences in English:

https://tatoeba.org/en/sentence...roved=no&user=

It's an enormous undifferentiated heap of sentences of varying quality. Some people do adopt sentences from it, but there's no inherently structured way to do it. By contrast, the number of sentences tagged "@needs native check" is much more manageable, and I review the English sentences with this tag periodically.

> What happens if one just disowns the translations they are not confident about? Do native speakers pick them up?

It depends on people and the language in question. For example, I sometimes adopt sentences (actually translations) that contributors whose French is not their native language contribute. For some of them, I am confident that their translation is likely correct because we have been doing that for quite a while. For others, I need to spend more time checking their sentences and I feel it more like a burden, to be honest (I'm one of those who proofread / adopted orphan French sentences of the Tanaka corpus, so I understand very well why native English speakers wouldn't want to check the current orphan sentences).

The key here is that the contributors I am mentioning add translations, often of their own original sentences. These translations are easy, or at least easy enough compare to their French fluency. So I feel happy to check and adopt their sentences. There is a sense of community, of "those users are also helping the French corpus". However, when complex sentences are un-adopted, I feel a bit upset because I wonder why someone would contribute something complicated that I, or someone else, would have to check, and, to be honest, correct most of the time.

Of course, as Alan mentioned, some people also use the tag @needs native check (nnc). Some native users then check their sentence and mark it with the OK tag, or the green review (this also depends on people).

In short, I think that if people respect 1) the guidelines Alan mentioned, and 2) the work of other people, most of us will be happy. (By 2), I mean not asking someone to proofread hundreds of sentences that were created with no confidence.)

You're welcome.

> Maybe it could be useful for corpus maintainers to be able to see only those sentences written by non-native speakers as well.

Would you use it to find sentences to proofread, or something else?

Maybe you misunderstood me.
For sure you can learn, I wrote it:
"You can use it for LEARNING, but you soon find out that those FEATURES are NOT ENOUGH to CALL this site a LANGUAGE LEARNING SITE."

The emphasis is not on the learning, but the contributing.

And what more: I only answered your question but you come with:
"I don't agree at all."

It is like: "I'm not sure if it is okay." "It's okay I think, but it would be great..." "No, I disagree with you, it's not only okay, I KNOW it's great!" "Why do you ask then?"