First of all, I'd say that map you use is a form of interwar gerrymandering, where administrative regions tried to dilute where there was a Hungarian majority area. Hungarians used a different administrative system (vármegyerendszer), which could be seen more neutral, because it was conceived before the age of nationalism, but I wouldn't recommend it, because it is not accurate.
What was indeed accurate, is not the A-H census of 1910 or the Romanian census of 1930, but the Hungarian census of 1941, where cross-references and other, highly sensitive methods were used to determine one's nationality. Teleki Pál, as a scientist, indeed wanted to have a clear picture of the national affiliations of Hungary. (Make no mistake, he had no good intentions with this, it was a pragmatic approach.)
It is worth to note that these lists were later used by both the Waffen-SS (to draft ethnic Germans into their ranks), the Eichmann-kommando (to deport Jews for the Holocaust), and by the Soviets and communists, to deport ethnic German families after the war. As my family was affected by it multiple times over, I am obviously not a big fan of the document, but I have to admit its merits.
The whoel census of 1941 broke down to settlements can be found here:
https://library.hungaricana.hu/hu/view/ ... 0&layout=s
The map of the administrative districts of Hungary in 1941-1944 can be found here:
http://dka.oszk.hu/009100/009160/kingdo ... agykep.jpg
To answer your question more directly, it was never considered, and that's no bloody wonder. Both the Romanians and the Hungarians knew that such a solution would not last, and place them for the other's mercy. So it's a no-no.
By the way... when the Second Vienna Award was conceived, a Romanian entrepreneur paid a huge bribe to Göring to modify the borders so the gas wells and the factories that used the gas could both remain on the Romanian side. Therefore the huge "sack" near Kolozsvár / Cluj-Napoca was nicknamed "Göring-zsák" or Göring-sack.
Also the Székelyföld / Szeklerland remained without rail connection, so the Hungarian government had to build a new railway connection.
"Everything remained theory and hypothesis. On paper, in his plans, in his head, he juggled with Geschwaders and Divisions, while in reality there were really only makeshift squadrons at his disposal."