Hello,
First i hope you didn’t take my comment badly, off course by just text it can be taken like rude but it isn’t.
The first thing is the recording. You need to recording with a good mic, one or two or more, who can record all, even subtle frequencies, in. This is the most important part, because then you will have a good, clear and not compressed sound to work with.
Working with sound from vidéos or phone isn’t good because, the mic used for the record wont have all frequencies, and mostly it will be directly compressed (off course a phone or cam mic can’t take all the db the plane is sending, it will limit itself directly).
Compressed sound is the worst thing because it tires the ear without really know you get it tired. I don’t know how to explain, but it will have a good “in your face” effect at first, but even if you reduce or add frequencies, first the sound will be less natural, but mostly you wont can make this compression to go. It will be always here if the source sound is. And that really tires the ears so it can be dangerous if someone play with headset and don’t really understand that the sound is tiring his ears. Even at a low volume, a compressed sound is tiring for ears on long time.
When you get good sound, well recorded, then you have to mix it with all other sounds you want to use. When mixing, the goal in this case is to make the sound near reality, but also to make it pleasant for ears in game. Its something who are made by feeling from the sound engineer, hard to explain, its like making a good meal and judging which spice you can put or no, and at which level… You must “take care” of ears even if it mean you must go bit aside the reality.
Also don’t make all sound stereo (except if the game accept stereo sound to be 3d localized but i doubt) and then make some sound in mono if it need to be localized in specific place in cockpit.
The principal difference you will feel between a good mix with good recordings and a mix made with bad records, it will be that with good records, you wont have to make it loud for feel it wide and “warm” around you, and really take you to another level without much effort. With compressed sound, as it is not as rich as good records, you will always feel you have to put that or this volume up.
Its really like cooking, but like cooking then, for have a good meal at end, you must have good products at start, if you don’t have a good record at first, took with good mics, without compression or saturation etc…Then you wont have a good quality sound at end neither.
I think i have been on an a320 but long time ago, i didn’t knew planes at this time. But i have been mostly in 737 (and never in cockpit anyway haha). I don’t doub you want to make it as much near what you find realistic. But from what i can see on pilot feedback in cockpit, they say that is mostly quiet, where you can take your headset off, its not the feeling we have with the fbw sound !
I hope you the best and good luck !
What i can advice to you its to try to get real sample, well recorded by pro with good mics of an a320 plane, inside, outside, instruments etc…, and then make your recipe from there, but not as easy to get i agree.
Cheers.