Title explains it, if you use any modded pickaxe on hard stone it acts like a gold pickaxe with no break slowness.

This is configurable. You'll need to add a setting in the armor config called "Slowdown", where is the name of the material the modded pickaxe is made of. Then you can set it to an appropriate value (10 matches wood, stone, iron, 2 matches diamond, 1 matches gold). If you try using one of the modded pickaxes without that value, the forge log will have an entry that includes the name of the material the pickaxe is made of.

Hm looks like it doesn't work with TiCon pickaxes, but the survivalist pickaxes work, thanks!

However I still don't know exactly what you mean with the config thing, do you have an example?

Next to your mods directory there will be a config directory, with an iberia.cfg file. There is a section of that title stone where you'll see lines like

    D:DiamondSlowdown=2.0
    D:GoldSlowdown=1.0
    D:IronSlowdown=10.0
    D:StoneSlowdown=10.0
    D:WoodSlowdown=10.0

Just add another one, following the same format, with the material type in the place of stone/wood/etc.

As for tinker's construct, I took a look at the code, and the problem is that the TiCon pickaxes aren't of type ItemPickaxe. They aren't even of type ItemTool, so there would have to be some serious custom code on my side to make that work.

Hey, look, TiCon marks their items extending from type Item. Maybe that way you can fix it?

Making TiCon compatibility would make the posibilities way more interesting.