Mmm; I have tried after a fresh reboot of the PC to assert it again, and quite surprisingly the "clanking sounds" isn’t there anymore... But another day, it is "coming back". It can barely be heard at times, but then is "strikingly present" (it is happening when eating non-stop/10ish pellets in turbo-mod).
Judging from the variety of it all, it seems it is the sound engine that "stacks or re-launch" a repetitive sound badly like i saw in other games (when a sound is stopped and another goes over it etc...) Hope it is only my PC here and not a all-around bug.
By the way, do you plan on updating "Random Lady-pac" with the same great options any days? (holding my breath is only good for snorkeling! ʕ◉ᴥ◉ʔ haha)