As it's perfectly rhythmical yet does not mirror any other part being played, especially in the intro before everything gets going, why would you think there was any chance for it to be accidental?
With the technology of the time, to remain entirely electronically generated you couldn't use any 'recording' of any sort with any real sound - so no real instruments, no real drums, no percussion, not even anything resembling a modern drum machine at that time. Some manufactured electronic percussion did exist, but it was extremely primitive & actually designed for organ accompanists playing in theatres & social clubs… about as far from the avant garde edginess Kraftwerk were aiming for as humanly possible.
The pinnacle of this 'organ accompanist' technology was the Roland CR-78, which did make its way onto one or two late 70s/early 80s tracks. The precursor of the 606 & the 808.
So, all their sounds were generated by synthesizers - 'primitive' at the time, entirely analog & driven by some quite surprisingly complicated interfaces. I don't know exactly what Kraftwerk used at the time, but no doubt it is documented extensively … somewhere online.
Without knowing the precise synth used for that percussive click, you can analyse it to be … obviously very short, by setting the sound's attack [onset] and decay [time to silence with the note held] to minimal, sustain to zero [there is absolutely no sustain] & release [duration after note-off]to as short as possible. Everything short, short, short.
In addition to this, through use of highly resonant filters over what may just be white noise, a low-pass filter that starts open & closes, again as fast as possible, meaning the perceived pitch of the sound falls within its duration.
I was reminded of a track from a similar time, by the British pioneers, Human League. They use a similar sound design - fast attack/decay with resonant closing filters - but quite a lot slower & deeper, so it's easier to hear the downward sweep as the filters close. It's in the 'kick drum' sound in Being Boiled [the album track not the original single] from Travelogue (1980). Whether these were the same synthesizer we may never know - the sounds just have a similar construction, albeit with a different end purpose.