you probably need to narrow down the geometry that you are after, mainly head angle and seat angle. there's a fair range of geo across the options you have there. also is your main priority xc/endurance racing speed, above all else? from the description of your terrain (i dont know the area though), it sounds like 100mm travel would be enough. you also need to work out your preferences and must-haves. e.g. is bb92 ok? need boost spacing? dropper post compatibility required?
i'm not sure if 67/77 angles on a short(ish) travel bike like that Carbonda FM936 would work that great for xc racing. who knows though, it might be way of the future. in the meantime, i find myself putting a setback seatpost on my 69/74 angle FS XC race bike, as the seat tube seems a bit steep compared to what i am used to (having said that, my recently acquired trailbike has a steeper seat-tube, but it is longer travel, and at sag everything gets a bit slacker). maybe this upcoming race season, i'll look into moving the saddle forward a bit (maybe even save a bit of weight and use my zero offset seatpost).
you should also have a look at the scott spark rc copies. e.g. hongfu fm258, pro-mance (not sure of the model, if it is the 9007 or 7007?), and some other resellers i cant recall the name of. i have one of these (the earlier non-boost fm058 from hongfu) and i find it close to perfect for the racing i do on it - since i have been racing on it (since mid-2018), my results have improved significantly (some of that had to do with diet and fitness though). i am not sure if a 120mm fork is what the frame is aimed at (it is designed for 100mm fork), but i don't think the geo would be screwed up by an extra 20mm at the front - in fact, it would put it in the same ballpark as the frame you mentioned that you quite liked - probably around 68.5/73.5.
if i could do it again, i wouldve got the boost version of my frame, and would run a 34t chainring. i had some chainring clearance issues with a non-boost chainline, exacerbated by running an oval chainring - had issues even fitting a 32t. the anti squat on this frame is such that it pedals unbelievably well, and i run it with compression full open, no need for rear lockout, even stomping up hills - my climbing speed last year was such that i have been relegated to the top grade this year. check out the climbing speed on kerschbaumer at last year's world cups when he was riding one of these frames (his is branded torpado, but it is the same frame as the 258). having said all this, i think the frame is designed around a 34t chainring - i am finding the anti squat is a bit too much with a 32t, such that the suspension is too firm under power and not as active as i am used to (i have had a lot of horst link bikes over the years). i am really splitting hairs here though - i have no intentions to change anything on my bike.
