[markozg]

Jerome,
there are some new foundings about this topic in Croatia. Czech crew who claim they flew a modern bomber, as David said are right. After all they knew what they flew and there are also many eyewitnesses in Croatia to confirm this fact.
But let's go in time order.
The unit from which Czech crew defected was equipped with Amiot 351 and 354 bombers, some of them camouflaged and some left in bare metal.
This type of aircraft had sufficient range to be able to reach Zagreb airport where it landed, while Amiot 143 could not do that - this is the 1st proof.
When the aircraft reached Zagreb, a young pilot was in the air making his training flight in Rogozarski PVT. This man was future post-war Yugoslav Air Force general Rendulic. In his memoires he recalls that a beautiful all-silver twin-engined aircraft popped out of the cloud and almost collided with him.
I spoke with Mr.Rendulic at his home several years ago and showed him some photos. Without any doubt he pointed at Amiot 351 as the aircraft he saw. - that is the 2nd proof.
Statements of the Czech crew - 3rd proof
In one of the stories long ago, there was a small note that citizens and passengers present on that day on the Borongaj airfield in Zagreb witnessed landing of modern sleek and beautiful shiny all-silver French bomber on the airfield. - 4th proof
Croatian Air Force pilot Ivan Matiegka who crashed in Caproni Ca.310 during one of his flights remembers "a beautiful French plane which was kept at the end of Rajlovac airbase and which wasn't flown by anybody" during his career at Rajlovac. Amiot 351 is certainly beautiful, while 143 is certainly not. -5th proof
You will notice that several reports refer to this airplane as beautiful and that is a very strong hint towards the type. Also in 1940 all silver 351/354 were not uncommon, while the bare metal 143 would be a rarity, especially from operational unit.
Now unfortunately there are still no photos but based on these facts we have at least some progress in this topic.

Best regards,

Marko