I was writing this before JKBart posted, but after reading his posts, and I can't help but agree. Still, I took the time to type it, so I'll post anyway.
(1/2)
Considering the physical factors and accomplishments of your average jedi knight/sith lord, I realistically don't think there should be many non-circumstantial victories of non-force sensitives (NFS) over force sensitives (FS). Even holding back, the FS should have the advantage; it would take a peak NFS to even contend. I can agree with your reasons for why a jedi knight might lose, and I also agree that your typical sith lord or dark sider really shouldn't lose without considerable circumstances. The only thing I could add to your explanations would be arrogance on the force FS’s part.
This can be exhibited in numerous engagements in the SWU, but I’ll only go into the ones I know which is limited to the TOR and PT eras:
KOTOR
Kotor I doesn't really have many offensive examples imo. Revan's victories before being retrained as a jedi are a testament to his raw force power than PIS. Canderous helping out on the Star Forge and Carth helping out in the Sith Base and Korriban despite the numerous FS present can be mitigated by the consideration that Revan was doing a lot of the heavy lifting. Pre-prime Bastila was only overwhelmed by Vulkars when she was unarmed, outnumbered, and exhausted. Still, premium NFS like Mandalore the Ultimate and Yusanis were easily killed by Darth Revan. Calo Nord was killed by a freshly trained Revan Redeemed. Bendak Starkiller was killed in the death match by mind-wiped Revan.
Kotor II mainly has HK-47 with a large jedi kill count, but he explains that is due to his circumstantial tactics rather than pure skill, ie. using explosives from afar, sniping, taking advantage of jedi morals as mentioned in the OP. With prep, HK could likely kill your average jedi knight I concede, but in the normal battle settings of the SWVF, I wouldn’t expect HK to be so lucky. Aside from that, Meetra’s companions are all force sensitive, so their victories aren’t really outliers, and you have Kreia dominating strong NFS like Hanharr with ease. Meetra besting Mandalorians and the Handmaidens unarmed is also a testament to the advantage FS possess. Canderous surviving his encounter with Nihilus can be explained by the many circumstances of that fight in general.
TOR
Now TOR probably has the most outliers in terms of NFS besting FS, but I mainly attribute that to the fact that they needed to make campaigns with NFS for variety, and as such, were forced to write some ludicrous situations to hype up the protags. There’s actually too many for me to remember rn, so I’ll list the more ridiculous ones off the top of my head:
• The Bounty Hunter somehow besting a Jedi Battlemaster who was prepared to kill
• The Bounty Hunter being given the option to kill Darth Tormen despite the latter’s shown ability to choke the Bounty Hunter out without a moment’s notice
• The Imperial Agent contending with Darth Jadus for any period of time
• The Imperial Agent killing Darth Zhorrid
I can’t think of much for the Republic NFS, but no doubt they probably have some too that require rewatching. Their feats just don’t make sense in the context of the opponents they’re facing imo.