In my informed experience, the weak cycling has nothing whatsoever to do with tolerances nor lubrication. As best I can determine, the tolerances within the operating system are appropriate with all moving parts free of fitment issues or interference. There is no discernable tolerance-stacking leading to either binding nor excessive play/slop. Similarly, I have been around the block enough in my 55 trips around the sun with 34 of those in the Army infantry to know how to properly and adequately lubricate a firearm. Thanks for the "pro tip" though....
The problem, as I correctly identified it, is weak Operating Springs which lack the necessary power to positively strip the top round out of a 5-round magazine stack from the Bolt-Catch/Bolt Release position. That's it, that's all. We're not talking rocket-surgery to properly balance an adjustable gas system once adequately stiff Operating Springs have been sourced and installed. The current Springs are adequate when a clean R18 is cycled indoors at room-temperature. Where the problem arises is when the temperature drops, lube wears thin, and/or the action becomes fouled. If there is no reserve of operating power built into the springs (compensated for with increased Gas Operating Pressure), then the rifle will falter at the first opportunity under field operating conditions.
Properly-tensioned Operating Springs paired with an Adjustable Gas Block are the answer to the R18 Mk2's primary identified shortcoming. Period.