yeah you end up with higher BB and slacker head angle by going to a longer fork than what is specced. Most forks these days in that range can be shortern or extended pretty easily just by internal changing.
Geo matter for climbing for sure but most bikes these days have such a steep seat tube that climb well and honestly making it slacker with a longer travel fork normally does nt affect as much as you would think. My Giant Trance has a 140/160 travel fork you can adjust on the fly unless the climbing is really steep Ill usually not notice if I left it in 160 mode, conversely unless it gnarly chunky descending I hardly notice 140 on the way down. with that said while riding the bike you can clearly feel the difference as soon as you chance it.
Getting back to the trek. I honesty would be fine riding a 1005mm rear travel. but would probably want 140mm of front travel for fun riding at the very least. You can also use taller fork and run them more into the sag if you want as well.
Long story short if you under stand what is being changed the factory set up isnt always best for everyone or best for anyone.... Take my Honzo for instances that bike is basically unridable on 120mm fork because you get so many pedal strikes, 140mm fork and you suddenly have less pedal strikes, and IMO a better riding bike that sags out to 120mm anyways. HJardtails are funny though as the geometery IMO should be slacker than FS because as the suspesnion compresses you are just making the bike steeper ,where as FS compressing both front and rear doesnt really happen.