During my first proper run as Germany that has been my experience too. Do note though that certain techs boost the capacity of air production facilities.

Yeah I found that the best I can do is to at least stop THEM having air superiority, by spamming massive numbers of 109's. Even then, I only match them plane-for-plane but have almost no CAS of my own.

Yeah the phony war couldnt be represented at all so far. In the current Test Version with the Avalanche update PDX finally enabled us to affect the air region ai, and the Allies are told to ignore Germany for a while

Agreed, very a-historical - Germany fielded the largest air force at the outbreak of war by far, and had over four thousand aircraft of all types available for the western offensive, nearly two to one over the allies. Unless you focus all out on air production, at the cost of literally everything else, you will never be anything better than par for at least a year, until your military capacity can even just begin to get a numbers advantage. Needs a serious re-balance.

As far as trying to combat it, you immediately need to start building mills strictly for fighters, and factories as you near capacity - even then it takes way too long to even remotely approach parity with the allies - plus there is yet still the US and Russian air to be dealt with. Even doing that there is literally no way to achieve true superiority before 1942/43 - by then your modern aircraft should have chewed through enough of the soviet and allied trash to get the job done easily enough.

i produced a hell lot of aircraft with a test-playthrough and noticed i lost 400 fighters during support of spain fascists... :)

I wouldn't be surprised if those losses are vastly due to ridiculously low (imo) reliability for aircraft, and are accidents. I can see quite shabby reliability for the first of a new aircraft type that are a big change, like going from bi to single wing, then radial engine to turbines - but base reliability pretty much always stays crap, and even with upgrades it is still pretty ♥♥♥♥♥♥. Doesn't make much sense either as upgrades are capped, yet years of warfare generating feedback from soldiers in general, pilots in particular in this case, reliability of equipment never improves. This needs to be introduced to base game imo, but small boosts to reliability should be commensurate with xp gained by said equipments' crews - and higher veteran level units take better care, and are better at doing it, of their equipment, which should also produce a small boost to reliability commensurate with veterancy level. Yeah yeah support brigades and upgrades blah blah, the fact is much maintenance and a significant amount of simple repairs - especially complex equipment like Tigers, we performed by the actual crew, and only major recoveries/repairs were done by dedicated repair bots. Air wing ground crews is much the same, they get better and better, thats' just normal, and reliability values should reflect this. Essentially consider that feedback from crews will, sooner or later, reach the ears of manufacturers and designers, and the better the crews knew their equipment, the better the feedback, and the better modifications the manufacturer can implement, increasing the reliability.

there is basically no way to do that because the AI will get like over 1K fighters at the beginning of the war from no where even though they have much less factories...

Historically, UK aircraft production overtook German production by 1940. So the problem is how to reduce UK peacetime production without reducing Germany's and without reducing UK production at war. Or is the problem actually France that only had 1000 planes operational?

As I recall, the owners of Hawker Aircraft were so certain of the coming of war, that they had 1,000 Hurricane Mk Is built without a contract. They had them sitting about their factories waiting for the government to order them. The main problem early in the war for the UK was that they couldn't train pilots fast enough to fill their squadrons. The UK outstripped Germany in production of single seat fighters in 1940 by about 10 to 1 as I recall. This was mainly because Germany's leader wanted the German people to "Enjoy the fruits of their victory's". Thus, the UK was running at war time production from the outset, and Germany didn't follow suit until around July of '43.

That's it for the history lesson there, as for the mod, the AI vastly outproduces any player in anything. I am able as Germany to get @1100 fighters into service by Sept '39, but the Western Allies typically outnumber me by at least 3 to 1. Thus my logistical services are wiped out by bombing, and advancing through the Low Countries slows to a snails pace. The Blitz in this Blitzkrieg seems to only come during thunderstorms. It can be quite frustrating. I'd still rather play this mod than vanilla, that became unplayable long ago.
I can say that today I actually found my copy of HoI I, the original, still with the box, case, and rule book. Lots of great memories there!