Just a few thoughts though:
I don't like counting the +2str from yugo pot, as I think the -4Wil penalty is too much to pay, but ymmv. Where is the +4 alchemical coming from a sustained basis? The main sources I can think of would be tensers, which is a pain to scroll every 1.5mins (but certainly possible), or else the fabricator's bracers (which isn't constant). I'm similarly not convinced that madstone should be counted as sustained, and I also find it difficult to fit in 2 str on FotW or LD (I generally find that I spend all points on abilities in those trees).
The +8 from psionic surge doesn't stack with titan's grip, but conversely titan's grip is 3 mins between shrines and fiddly to use (swapping out gear for 1 min buffs is easy to forget). Thats why I count it in the fighter's sustained str but not the monk/ranger.
On the +8 enh, your maths looks like the 32 includes this already.
=3.5x7(mean damage from 2d6)+7 = 24.5+7 = 31.5
The upgrade from +7 to +8 changes the above to 3.5[2d6]+8, or 32.5
If its working differently, so that the +8 is stacking on top of the +7, then its definitely a bug.
RE: use of stances - my point was that the 12F/6M has more flexibility in choice of stance than the 12M/6R. In order to keep damage competitive between the two, the 12M is forced into using earth stance. If the 12F goes to earth stance, it ends up with similar hp (possibly slightly higher due to fighter levels) and similar PRR, and mean damage per shot is about the same across both builds (with the 12M getting higher crits on natural 19-20 and the 12F getting slightly higher damage on natural 2-18). However, the 12F/6M isn't getting any of its damage in this case from the earth stance, so its choice of stance (for damage calculation) is more or less irrelevant.
If the 12F/6M switches to ocean, it loses 1 damage per shot due to the -2Str malus, but conversely gains a few % dps in 10k mode. At base damage >50 (which based on both our numbers is certainly a given), the 12F/6M actually gains dps by going into water stance. This is the basis for my statement that it has slightly higher dps than the 12M/6R. If the 12M/6R switches stance, it loses 8-10 damage per shot per your numbers, which is partially offset by gaining 8% or so from the additional wisdom; netting the two, it loses about 4-5 damage per shot.
Ultimately, I think the two builds end up at similar damage output, with the 12F/6M looking like it overtakes the other (on paper at least) by a very small margin. Its possible that a fully max'd out build, with all relevant PLs and completionist (like your Sithali build) is level with the 12F/6M when all its buffs are up, but for most players who don't have completionist or the full set of ranger and monk PLs, the 12F/6M will almost certainly be ahead (but again, by a trivial amount). Its basically a question of whether the fighter's +7 per shot from weapon spec and kensai enhancments, and its +5 per shot from greater sustainable strength (+2 fighter, +8 psionic) outweighs the 12M/6R's +10% base damage per shot + 3 per shot from ram's might. If you remove the +8 psionic by giving the 12M/6R access to unlimited use of titan's grip gloves (say 3 or 4 pairs) then I accept that the 12M/6R nudges ahead, but I also think this is an unrealistic assumption.
Having said all that, I can certainly see the other benefits of 12M/6R - I imagine it may be a much more 'fun' build due to faster run speed and various cool monk features that the 12F/6M misses out on.