If you e.g create a Cmaj chord and add a b9 (Db) to it, the editor produces a wrong result by adding a 6th (A) instead. This also happens with #9, b5/#11, #5b13…
I can confirm this behaviour, still the wrong tensions for b5/#11 and #5/b13. Instead you get a 6/13.
I am getting wrong results for other combinations aswell, turns out that more complex tensions often results in an 6/13 …
And when it comes to minor chords, b9 and b11 results in adding an 9.
And to go on: Choosing a minor chord with the tension #5/b13 instead resets the Chord Editor, and deselects the chord and tension I have selected.
By the way you can’t for example select the tension 11 (it is “greyed out”) for major chords. Maybe that’s a conscious choice of Steinberg, but I think it’s better to have more freedom as a music creator.
It seems that the Chord Editor is quite buggy in Cubase LE 13, at least on Mac. Is that the case for other Cubase versions?
I was planning to buy Cubase Elements to use Cubase to start my orchestral compositions, then moving on to do the orchestration and mixing in my main DAW. I love the idea of the Chord Track and Arranger Track. I was thinking of buying Cubase Pro further down the road, to make Cubase my main DAW. But I just have to wait and see, until these issues are resolved.
I’m running Cubase LE 13.0.20 Build 148 (Intel) on an MacBook Pro 2019, Intel Core i9, Mac OS Ventura 13.2.1.
Same already on Cubase 12.0.60.
Even if one uses Live MIDI Input. The chord gets detected correctly but the wrong keys are being displayed/created.
Thanks for these suggestions! Setting the Voicings mode to Basic (instead of Piano) seems to solve the issues. The downside is that you lose the bass note for the chords in the chord editor when you switch to Basic.
Unfortunately you are still not aloved to use the tension 11 in a major chord.
But it is at least a big improvement to get the right tensions for those tensions you are able to use!
" The downside is that you lose the bass note for the chords in the chord editor when you switch to Basic."
It’s relative: a bass player might love that! 
Anyway you can always drag chords to midi track/s and then add or move voices.