First of all it was a honor and privilege to be of assistance
Now for the campaign itself.
I was pleasantly surprised by the different mix of units, even the horsetransports were a nice change. I must admit, that at first, i wasn't sure if i would make a DV because most infantry units didn't have a transport. But it quickly seemed that you had covered that, or even calculated that a DV within the given time should be possible. I do have the impression that before you threw this three scenario campaign at the "lions", you took your time to test it thoroughly yourself.
I did lose a couple of auxiliaries caused by polish surprise attacks. I don't like units to watch and do nothing but here it was definitely not the case.
Perhaps you don't know that the AI likes to withdraw damaged air units and doesn't use them again before fully recovered. Also, when i took the polish airfield, they remained dead in the sky. A second polish airfield, even in a corner, could remedy that. I might have lost more units if they would have remained active till the end. The balance feels right, prestige also. Moving to the second scenario, i bought another artillery unit. I was glad to have a scout car, those forts are really nasty buggers. I felt like not having enough units under my command but somehow i managed to take everything, losing a few auxiliaries underway. The victory hex at the left of the map might have been even more difficult to take, if that 8 str inf unit would attack before i took the city hex, and not after. The only thing i missed in the first and second scenario is a tank vs tank battle. Ofcourse i don't know if you went for very historical or if you gave yourself some latitude when placing the units but still i missed enemy tanks. It is very interesting that it is possible to purchase an armored train but without a rail hex to deploy, ofcourse it is no sense to purchase. The second scenario felt right to me again, balance and prestige wise. In the second scenario i also had a portion of luck because 2 of my infantry units finished with 1 strength only.
The third mission was an answer to my prayers...tanks! This mission felt like a blitzkrieg mission which i finished in 13 turns. The upper and lower right corner objectives were taken with a scout car. Perhaps a defender could be placed.
On the other hand, perhaps not because those victory hexes are in the corner of the map. Out of experience, players like to take objectives that can be encircled and thus attacked from several directions. Overal for the third mission, it's the easiest one. The slowak fighter is no match for the I-16 due to its fuel range and strength, I couldn't use it in action because of those limitations. I bought a bomber here and i was lucky it survived but i could only use it in 3 turns altogether.
The same remark goes here about the only airfield for the russians. When i took it, the same happened. The russian fighters went on strike.
Another hint to make it more challenging. Give the player more core units and less auxiliaries. Generally a player considers a core unit more precious than the expendable auxiliary. I use my auxiliaries more like kamikaze units or throw them as a bone to the enemy . I would never do that with my core units on purpose.
Than i have two general remarks. One, a lot of units had no movement sound. I did load it into GME but didn't place it anywhere. Second, perhaps you could compile a small list of the slovak classification of the units into english. I have the luck to understand several, because it is rather similar to polish.
Augustin, i'm your first fan

. Playing an axis minor can be as interesting as playing one of "the big four" and you have proven that. You consider yourself a beginner, but when i look at the scenario's, you are definitely way passed that phase.
Thank you for your Axis Slovakia mod and i strongly encourage you to continu this. Ďakujem.