Have the same CTEK charger.
Spoke with CTEK last month. Basically if your car has a start stop system whether an AGM battery or EFB (Enhanced flooded Battery) (as my Volvo) then use the AGM mode.
If not then use the standard car mode whether sealed or not.
Likewise, to assist further.
Those with start stop that have EFB batteries you can upgrade to AGM, but not the other way around. The definitive answer will be in the manual if it states otherwise of course.
For your information. 
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