Sealants such as Klasse SG, Zaino, etc., typically don't hide or remove swirls. In fact, with a better reflection on the surface, swirls can become more apparent.
AIO is a cleaner, and typically doesn't remove swirls either (although some here have removed swirls with AIO).
Swirls are actually very fine scratches in the paint, and to completely remove them, it is best to polish before applying the cleaner/sealant. There are several polishes available from 3M, Meguiars, Mezerna, 1Z, Griot's Garage, etc.; and they work very well for this purpose.
Proper preparation is the most important thing for a good result. Without proper prep work, it doesn't matter whose sealant you apply, it's not going to look good.
Imagine painting a car without proper prep work. You'll see every spec of dirt, every old chip/dent that was there, fisheyes from where oil remained, etc. These 'problems' actually wouldn't be problems with the paint, but rather would be problems of poor preparation.
Without proper preparation before applying the Klasse, you won't get the best results possible - though admittedly, you may get results that are acceptable to you - and this is really what counts in the end.