Exactly. I guess Benes and Beck were not best leaders and with not much vision for future.Poland was, in theory, allied to the USSR in 1944. If Nazi Germany is the greater threat, Benes and Beck could each grow a brain and work out a deal. Something along the lines of 'one year after hostilities with Germany end, Cieszyn will have a plebiscite overseen by Romanian troops to decide who gets what.'
The issue is that the Poles, for some inexplicable reason, thought that the French and British would actually do something for Poland if Germany went for them next. This blinded them to the consequences of allowing a German takeover of Czechoslovakia. If Hitler or Chamberlain start talking about Danzig or the Corridor (and Hitler did, apparently, start raving about German minorities elsewhere in Europe at Munich, so it's not implausible), the Poles would be much more likely to work with the Czechs.
If they do that, they could probably beat Germany (particularly if mutual ally Romania cuts off Germany's oil). But what then? They don't really have the capacity to occupy and demilitarize Germany, so they'd have to formalize the new Poland-Czechoslovakia-Romania alliance, as a future deterrent--a new Little Entente. Settling the Cieszyn issue will be in everyone's best interest to achieve that.
Czechoslovakia would be probably willing to go with Tesin plebiscit. Very likely bussinesses would stay inntheir owners hands and special relation for region could be worked out. Czexhoslovakia on other side may get plebiscit in Polish Spisz and Orawa villages ceded to Poland in early 20-ties and with Slovak majority.