As the title says the curved rails that appear to be changed by the train tunnel mod are blocking airplanes. The tunnels are blocking as well. Is there a chance to change this? Otherwise aircrafts become useless inside a base as transport vehicle with AAi Mod. Lucky me I haven't build anything in my tunnle yet. Aircraft Mod seems more important for me. But I'd love to use train tunnels as well.

So no feedback here?

Nope, same as with the other mod (hovercraft I think). There is no way to prevent other mods to use the same non-vanilla collision masks as other mods. I use that non-vanilla collision layer to prevent placing tunnels on curves, they use it for their own reason. If I change it to another layer it will probably conflict with the next set of mods.

I think I haven't really understood it. Point is that planes can cross basically everything in vanilla game. Why does curved rails block when your mod is in use?

Curved rails are on another layer so tunnels can't be placed on curved rails?

Is this maybe changed with a single line? If so, may you assist me to change it? In case this is possible I would try to find a setting that works with my mods.

It should be possible to have a startup setting for the collision layer.
But in fact I believe you can use something like
https://github.com/wube/factorio-data/blob/master/core/lualib/collision-mask-util.lua#L268
which should, ideally, give you an unused layer.
To be on the safe side, both mods should use that.