After all "want to" is still regarded as a better English than "wanna", is it not?

Perhaps with unowned sentences, we should weigh things:
On one side, changing sentences may be a potential loss of diversity, but on the other side, an unowned sentence isn't worth much.
So when a native speaker takes the pain adopting sentences, shouldn't we allow them to change sentences as much that they sound good to their ears, in their own variety of language? Because that's what ownership of a sentence is meant to be. Of course, changes should only be on a stylistic level.

Sometimes I wonder, why the old sentence pairs from the Tanaka corpus are held kind of "sacred" here. Why not just get rid of all the so far unadopted sentences? As often as not, even a mediocre speaker of English can tell they're unnatural and by now, there would have been plenty of time to change them, if someone thought it was worth it.

It seems to me that "wanna" is not a word in any standard variety of English, either British or American. It is merely the sound that is produced when a less articulate or less educated speaker says the words "want to" rather quickly. A phonetically somewhat similar phenomenon occurs when an educated speaker of Scots English produces the word "cannot": it is realized as "cannae." To include such variations, we may need to add a new language flag with NNS (for Non-Normative Speech) superimposed on the UK flag.

There may be sound reasons for including a number of variant but normative means of expressing the same idea in the various languages represented at Tatoeba. But I think that attempting to include every poorly enunciated phrase as a recorded differentiation from some standard variety of speech is a bad idea that will dilute the usefulness of Tatoeba as a language learning resource. People preparing language learning texts are surely aware that language shifts on a continuum from Prague to Warsaw, or from Oslo to Stockholm, but because they have to teach SOMETHING, they'll pick the language style most commonly used in the capital city, and thus you have both Czech and Polish, and also both Norwegian and Swedish. To imagine as well dialectal stratifications that have to be labelled by the age range or education level of the speaker will magnify the problem of the language learner and lead to utter bewilderment.

I agree with CK. You should return as it was at the beginning. We could add tags such as slang, non standard grammar... But we need such words, also. Many languages have similar things that are equivalent to "wanna" expression, so it could provoke creating more enriched vocabulary at Tatoeba in many other languages.

You (Obj'Sea) appear to operate on an assumption that people only come here to learn the standard variety of a given language. That assumption is quite wrong, apparently. There are all sorts of slangy sentences here.
On a personal note, I don't like it when people let their personal opinions get in the way of variety. That is, of course, because I happen to be its proponent.

Silly sentence now reverted and unadopted. Whoever wants this thing can have it. I'm sorry I spent any energy and time on this.

>>It seems to me that "wanna" is not a word in any standard variety of English, either British or American. It is merely the sound that is produced when a less articulate or less educated speaker says the words "want to" rather quickly.

@Objectivesea. I agree with you, and can't see the point of "wanna" etc. In Australia people say "gunna" (going to) "'avta" (have to), "avago" (have a go), "gotta" (got to) etc, and I can't see the point of including these either.