Hi @Fardnury this is the first time I have encountered this problem to be honest, but I think we can figure something out and get you back to your project 
. Thank you for the information you have provided, it has helped me in trying to replicate your issue to a certain degree on my end. With the new motion capture system, it is expected to run into a few problems since it is still under “experimental”, but there are ways that we can work around this specific issue you are having. From what I have gathered is that you are able to get the animations correctly exported and assigned but the issue is that it has a permanent rotation from the start. In my opinion I think your best bet is going to be to use “additive layers” and then baking them so that it becomes it own standalone animation with the corrections already applied. You might find yourself using them for other animation issues in the future as well depending on the results that you get from the motion capture system. Below you will find step by step instructions on how to apply this.
Setting UP
Note: My layout out may be different from yours, but I have set it up so that it makes it easier for me to have all the resources we will need in one screen for presentation purposes. Below you will find an image that breaks down what each section contains so that you can convert it to your own personal set up to make it easier for you to follow along.
Okay with that out of the way. We’ll start with a fresh Sequencer and add the character we would like to work with to it.
Now let’s add the animation you would like to change to the character by muting the Control rig first (click on the small eye next to the headphones) and adding the animation by clicking on the “+” next to animation and select the animation from there.
My character is animating facing/ animating the opposite way from how I would like it to be
We will be using “Additive Layers” to fix the orientation and bake the animation. from there on the new orientation will have it’s fixed orientation permanently.
For that we will bake this animation to the control rig we originally muted at first
Bake to Control Rig
Right click SKM_Quinn_Simple → Bake to Control Rig → Select your character’s control rig → click on “create”
You can now delete the old animation you assigned, the entire animation has now been transferred to the control rig
Adding an Additive Track
Let’s click the CR_Mannequin_Body’s “+” sign and select “Additive”
I’m selecting the “body_Offset_ctl” and rotating it to -180 degrees facing forward and keying it so that it saves the changes. And when I scrub thru the animation, we can see that it’s playing in the right direction.
Baking the Animation
Right now, all of this information is living in the control rig so we need to go ahead and bake this information so that you can use it as a standalone animation.
Right click “SKM_Quin_Simple” → Bake animation Sequence-> Select the folder and name of the animation → Export
Now you should have a standalone animation sequence with the corrected orientation that you can use moving forward.
I hope this helps, if you run into any problems or need further assistance, please let me know .