Regarding sequencer:
"External sequencer" refer to your DAW - your host for Modular.
See the attached image. The trigger you select in the popup menu controls the sequncer. The "Externals ..." refere in your question to you DAW/ Host.
Regarding latency.
First i'm not a technician. I can't evaluate all the specs in your attachment. I assume your system is balanced, and the part match eachother so there are no bottlenecks.
In Audio Production a high CPU clockrate is still important as many applications only use a single core for a task. Many things don't use multicore. But you do have a quite high clockrate at 4.0 GHz. I don't know about AMD. I use Intel I7.
16 GB RAM is very good.
You have many disks, and i don't know what you use for what and if the WD disks on the SATA 3 (6GB) connections are SSD's or not. I only use SSD's on my main PC. If you use HDs then be sure it's at least 7200 RPM. 5400 RPM are very slow. I prefere SSDs. A slow harddisk can cause latency.
I'm a bit concerned about all the different speeds/ rates i see. But only because i don't im they are used.
Check your computer performance in Windows Ressource manager. Both CPU, memory and disk when you exsperience latency.
About soundcard/ latency (I also have a Komplete Audio 6): Be sure you use Komplete Audio 6 ASIO driver.
The latest drivers and firmware can be downloaded here:
https://www.native-instruments.com/en/support/downloads/drivers-other-files/Older drivers here if you login on your account and search your product:
https://www.native-instruments.com/en/support/downloads/updates/Also if need to you can contact NI support.
Also see this article to check and optimize your system and your soundcard settings:
https://www.native-instruments.com/en/support/knowledge-base/show/3671/windows-tuning-tips-for-audio-processing/Perhaps try and use the LatencyMon you also can read about and find a link for in the article.
I would say, that you for most part should be able to run your soundcard at the settings you have.
Sometimes 48000 Samplerate work better than 44100 HZ. That you can try out.
Also the buffer might need 192 samples if you do very demanding things that stress a single CPU core.
The USB buffer shall match the latency. You should be able to run the 2 ms you have, but it also depend on how your computer system perform. If you have USB underruns you need to raise the USB buffer.
Also be sure you use the correct USB cable, and it's not defect. That can cause issues. Be sure the dimension (Thickness) is correct.
Have a look at this:
https://www.native-instruments.com/en/support/knowledge-base/show/2085/choosing-the-correct-usb-cable-for-your-ni-hardware-device/EDIT:
About your DAW.
Be sure it is set to use more than one of your CPU cores. In m DAW i have to select the cores my DAW shall use. I let it use all my CPU cores.
EDIT end.
That's what i can do to help about this. The rest is about if your hardware work okay or not. That would need a technician to find out i guess.
I hope this is enough for you to get this working tiptop.