Hi
I have read your post several times before offering my own thoughts on the issues you are having.
Sorry I too have no TLDR version of this.
Full Disclosure: I am NOT a game developer but I am an animated film maker who uses Iclone pro pipeline Daz studio, natural motion endorphin, with both Lightwave3D 2015 and Maxon Cinema4D as final render destinations for the animated walking& talking Daz peopleor Iclone avatars.
I am also a Daz genesis clothing developer for my own internal usage
First and respectfully, IMHO it may be a tad unfair to Say:"Just make sure your workflow matches on the In Side and Out Side in lieu of simply assuming Reallusion's tools have been thoroughly tested to automated goodness."
It is not reasonable IMHO to expect reallusion to have parsed every conceivable variable, introduced by a highly customized pipeline such as yours,or mine for that matter.
Based one what you described and My own experiences with Daz genesis models I estimate a more than 95 percent probability
that many of your problems are related to the "over engineered"Daz Genesis model rigging and their Daz studio related dependencies that give them their "unique" functionality within Daz studio.
It comes as No surprise to me that your team is still using the "Old" Genesis 1&2 era Models,as I only recently began using Genesis 3 in my animation pipeline after an inexplicable discovery* by another user in the Daz forum
(* more on that later..I promise)
There are caveats and outright bugs in the genesis platform that typically only become apparent to us character animators.
For example: the "limits on rotation on/OFF" caveat.
My typical Motion retargeting workflow consists of importing a naked G1or G2 to Iclone 3DXchange and leaving him/her there waiting.
Over in Iclone I create my "first Pass"major body motion with a simple CC Avatar in his underwear, using the powerful motionbuilding tools of Iclone pro.
When satisfied with the shot or shots,I collect clip & send to 3DX where it retargets to the Naked Daz figure perfectly,Add to perform,export BVH after selecting hip as the root.
Open BVH file in free BVH viewer app for quick check and import to Daz studio.( Good job reallusion!!!)
Now the "problems"
The animation looks "Off "Daz studiosuch as the guy who was raising his arm at a 90 degree angle in Iclone and 3DX is now only rasing it to 70 degrees.
Reason??.. Duuh... in the daz studio scene manager,I forgot to right click the top of the Daz genesis 1 or 2 Figure heiarchy and "select children" and then go to edit/ figure /rotation limits=OFF.
Now re-import the BVH and I get true fidelity
show stopper ?? well.. No.. but those default rotational limits on a freshly loaded Genesis figure Have ZERO logic unless perhaps you are loading Canned poses for sexy pinup still render with DS Iray.
I also Use the Graphmate spline graph editor for my "second pass" body & hand refinement in Daz studio,again on a naked Genesis figure at base resolution for best viewport performance in Daz studio.
After adding any Facial animation lipsinc with the old but venerable mimic pro3 or the Daz mimic live for G3 and higher, I save as animated pose file (duf) to be applied to the fully dressed & hair quoifed actor who will be sent to a Maxon C4D pre-lit set/environment for render as an animated mesh via .obj/MDD from animate 2.
Now Load my fully dressed actor
(TURN OFF ROTATIONAL LIMITS!!) and apply the animated .duf file I Just tweaked and saved from the naked version of him/her 30 seconds ago
and on frame one his/her lift arm ignores the motion of the saved duf file and pops to the default 90 degree angle of the "t-pose"
This bug repeats like the rising and setting of the sun.
Open Graphmate (Paid add on) and delete first key and arm returns to proper position from the saved .duf file.
Finally DAZ inc & Genesis 3& 8.
With Genesis 3 Daz added four new twist bones
(one for each limb) and completely Broke compatibility with every BVH mocap file from the previous Daz/ poser generations
and every existing Daz aniblock from their own nonlinear aniMate 2 system and ,for a while, the Auto recognition template for retargeting in Iclone 3DX until RL updated it for version 6.xx.
( we 3DX users still had the option of a manual remapping
and saving the template of course).
But so what?? until the recent version of DAZ studio 4.10
Genesis 3 would NOT accept her own BVH files in Daz studio created with her OWN rig in Iclone/3Dxchange nor from a characterized version of her from the mighty Autodesk Motionbulder.
Before DS 4.10, Anyone wishing to move "up" G3 would have to abandon his/her entire library of motion files& sources from as far back as the Daz Mike and Vicky 2 days
To add Orwellian insult to injury they later promoted Genesis 8 as
"The most backward complatible daz figure in history"
When we demanded to know why the extra limb bones??
their forum moderators would all parrot a canned response of
"that is how the pro applications handle limb twisting".
DAZ DOES NOT TEST GENESIS FOR ANIMATION!!.
After two years of scathing criticism by myself and the other two animators in the Daz community, an animator named wendy accidently applied an animated duf file created with the original genesis 1
to a genesis 3 figure and it worked!!
Yes... animated duf files created with genesis one will work on G3 and even G8 after you apply a freely available T-pose morph to G8 to undo the Default "A-pose".
Only a G1 duf file!!. Not a G1 BVH from Iclone or duf from Genesis 2
Daz had two years to shut up us LOUD complainers by saying:
"If you guy/gals are such character animation pros ,why have you not noticed that a Genesis 1 animated Duf file works with G3/8"
They said nothing because they knew nothing, as this was an animation issue and their target demographic are the digital content hoarders from the still render hobbiest community who buy from thier store.
Your problems may be All be Iclone pipeline related.
The DAZ genesis Models ,even with their bugs, offer a single man, animated visual storyteller like myself alot a instant versatility
particularly for the sci fi genre in which I work.
However I would be curious to know of any Commercially successful game titles made using Daz genesis models in the character pipeline.