Agregat Kaltmann k-ak2500 pro: Voltage Stabilization Check, Bulb Blinking, Connecting TV/Fridge

Today there was no energy and I started the generator.
I noticed some bulbs had a blinking effect.
The manual says that it has a voltage stabilizer. The generator was loaded with about 400W.
How to check if the stabilization is working?
Can a TV or fridge also be connected to such a generator?

Aggregate connection method:

The fuses were unscrewed from the riser (single-phase generator) from the usual plug in the box, I distributed the phase to three wires and the muff was connected to the power installation in the house so that the entire installation was live. (Or maybe I used the wrong way to connect to the installation?)

My friend regarding voltage stabilization, if it is the result of the seller's instructions and statements, he should have it. Check for yourself, remove the cover from the fan side of the generator and you will see if the device has them (there should be brushes similar to the alternator). Maybe the engine speed should be increased to eliminate bulb flickering.

For your own good and other people, read the generator manual, because you risk a lot with connecting the house power supply from this generator. Moreover, it is not recommended for powering electronic devices.

Tomorrow I'll spin it up and check it out.
Will it be possible to connect electronic devices after connecting an external additional stabilizer?

However, it has this stabilizing module.
Will it be possible to connect electronic receivers to the aggregate after connecting the second stabilizer?