They say that they use a sigma delta ADC and chances are this would be the AD7175 and not an extra seprate build one. The AD7175 is a slightly off choice, more made for high speed, but still OK. The relatively fast ADC may be used to get still relatively fast trigger / start of a measurement. A slower SD ADC may have too much delay at the start.
Noise wise the AD7175 should be good enough, even with a background check of the ADC and ref. divder gain.
Chances are there is a µC for the ingurad part, as there is a 2nd crystal or clock generator besides the one at the ADC. Chances are the 16 pin chip next to it and close to the signal isolators would be something like a µC.