Greatbow balance

That’s not how the game actually works.
You can start with
Str 18
Dex 4
Int 8
Per 4
on any character even with multi-pool system, no mutation or cybernetics involved, no skills or traits exchanged.
Dex 4 and Per 4 are largely irrelevant if you know what you are doing: they don’t limit your ability to use the bow, just make it somewhat longer to aim.
You don’t need to hit things at full range for that 18-str monstrosity to become overpowered. No, you hit things 1 tile away (where your Dex 4 and Per 4 don’t really matter) and one-shot them with a head-shot.
To be more specific, you start aiming beforehand, and then actually release the arrow once the target gets close enough to get a guaranteed hit/head-shot.

The difference is, melee enemies have 0 chance to retaliate even if you miss or fail to hit them with the bow as long as you left an extra tile for them to move before they can actually engage. Not the case with nodachi or whatever — if you miss, you will be attacked.
That, and you can pre-aim a bow shot for effectively guaranteed hit/head-shot. Something you can’t do with melee.

Archery is easy to train, perception does not matter if you are attacking from 1 tile away.

What makes you think normal arrows and normal bow materials are even capable to withstand this kind of forces for more than one shot?
I’d say this kind of contraption should use heavy sticks for arrow shaft (one stick per “arrow”), and still have a pretty high chance for the said arrow to break. Because, you know, if it’s dealing 35+ point of damage, 35+ points of damage are dealt to the arrow. Bow string should be something much more durable than simple strings you use to hang curtains (i.e. metal/kevlar/etc, or AT LEAST a couple of ropes).
And even with all that 35 base damage is ridiculous. That’s almost twice the composite crossbow! I mean, if character can craft that kind of “bow”, why not an equally oversized crossbow with, like, 50+ base damage?
And I don’t mean the heavy one with 6000 reload speed that you can only craft via a book, I mean just oversized DIY monstrosity that you can reload pretty quickly with you bare hands using just your 18+ str.

P.S. Bottom line: 35 base damage is still pretty ridiculous for hand-made bow when composite crossbow has 20 base damage. Things just don’t scale up this way in a game. 35 damage make it an equivalent of full-blown heavy assault rifle. That kind of power should damage the bow and arrows with every shot unless all components are high-quality steel or better.