Thank you very much. I guess that’s why our AEGs never had moisture or ice along the back wall of the refrigerator given their combi fridges use two compressors. I appreciate the explanation. And when I’ve never had to worry before about checking the trough and drain, I realize I now will (though I should add some of this water has drained into the vegetable drawer, not only the angled posterior trough). I wish I had known this before I spent so much on an expensive model of the Bosch. I could have gotten another AEG for the same price. I changed because both AEGs had some noise problems, but that bothered me far less than all this ice and moisture in my fridge does.

As a post script, when I went back and looked at the sales page on Bosch for my model, it did state exactly this when I clicked the information button for it’s No Frost feature:

“Frigoríficos combi con NoFrost

La circulación constante de aire seco evita que se acumule escarcha en el frigorífico o el congelador, por lo que no tendrás que descongelarlo.”

 

Yes, this is normal for fridge freezers with only one compressor.
The back wall of the refrigerator section is a continuation of the cold plate (evaporator) of the freezer section, so it gradually becomes covered in frost/ice once the freezer gets really cold.
This cools down the refrigerator section until the thermostat, which senses the plate temperature, cuts off the compressor at around -30°C, which should correspond to a fridge temperature of around 5°C or so.
The frost/ice gradually melts, maintaining the fridge at ~5°C, until all the ice has melted and the temperature rises to ~6°C, at which point the thermostat cuts in again, restarts the compressor, and the whole cycle is repeated.
The cut in point of the thermostat, ~6°C, is fixed, and independent of the temperature setting of the thermostat.

The point at which the compressor cuts in and starts to freeze again depends on the ambient temperature where the unit is situated, and the frequency at which the door is opened.
This means that the unit should be purchase in the area where you live, so that the ambient temperature for which it is designed is correct.
Also, the unit won't work correctly if it is situated in a cold place such as a garage or outhouse, as during cold weather (below 6°C) the compressor will never start, and the freezer temperature will rise to the ambient rather than maintaining the -15°C minimum required.

EDIT: The water produced by the melting ice falls down into a trough, which drains into a container on top of the compressor.
The heat produced by the compressor is usually sufficient to evaporate this water before it overflows, but the trough, drain, and container should be inspected from time to time to ensure they are not blocked.

Just saying........................