Any improvement of this sentence is welcome.

Well, the sentence is ok, but why would you discuss something with a horse?

And Why dont you keep your sentences? Its okay to have "bad" sentences. Other users will tell you what to change and youll follow their advice or not. If you unadopt a sentence theres no one responsible fo it anymore, so suggestions for a change mighb be unheard.

I asked for improvement since I'm not sure if the tense is the most appropriate (maybe some ...ing would be better...). So it was basically aimed at native speakers.

"I would discuss [something] with my horse." means It's really uninteresting (at least in French that's true). I could as well answer to someone "Yesterday I ate an apple." (as if it were as interesting as his boring story). This is irony.

I "hear" you very well. :o)
I choose to let my sentences free after I'm done with them (while keeping a list of them), so it's easier/faster for others to improve them if they want even if I'm not around.

Yup,
The French sentence is an idiom to say that one can't be bothered.

Et elle m'a bien fait marrer :P

My opinion is that one should try and translate an idiomatic expression with another one, because direct translation doesn't carry the same meaning as the original.

If a native speakers had some funny idiomatic way to say "I can't be bothered" or "I don't give a damn", this would perfectly fit here :)

CK you have much imagination :oP

Hm, I have some concerns about unlinking.

As a direct translation, the two sentences match perfectly. But consider what would happen if the sentences were to be separated : the lonely English sentence would then be translated into French, resulting in a duplicated sentence.

In the case of idioms, I think it might be useful to have both a literal and figurative translation. We could tag the translations to show which is which. This would be a lot nicer once Tatoeba supports having tags on links.