Actulally Troukk and swbf2lord both of you are correct.
They do tend to roll a lot of 20-s, and they do have the enhanced critical range.
Also both the DFWA and the SK have pa and i think IPA as well. These two the massive amount of crits they land, and the IPA is what makes them dangerous.
However usually you ahve to fight a skeleton knight in a less open area, which makes them in my oppinion harder to kill.
A deep forest alpha can be more easily disposed of if you have a spotter in group. Also their skins grant 44 gp, not to mention useable leather for midlow level.
So i think their CR needs not be changed. With carefull planning a group of level 3-s ( 3 level 3-s) can dispose of them.
I had lead some hunting parties to kill deep forest wolves in the last NCW. And i still on occasions lead new low level folks and show them how you can dispose of them with the least risk.
The only thing that is annoying in them is the high demand of animal empahty which is required to befriend them, which with an CR raise would become even higher, and their saves. (They have if i recall well +4 or +6 to will save, makeing them quite hard to be held via hold animal spell.)
I think the deep forest alpha is quite fitting for it's range. If you start to up it's CR, then thereafter quite a chain of monsters CR should be raised.
Since this creature requires a spotter to be easily fended off, whereas certain other creatures require in game ITEMS, or certain spells. (Magic weapon, magic varnihs +1 items etc.)
So actually i woudl leave this creatures CR where it is at, this is perhaps one of the FEW creatures on the server, that allows for nature kind of classes to shine a bit. (especially rangers)