But the place of articulation kinda flips, from rear consonant/front vowel (kiki), to front consonant/rear vowel (bouba).
If you flipped the voicing, it'd be 'gigi' vs 'poupa', which to my ears at least, is a lot less clear cut.
Yeah this I know, by "bouba" being opposite I meant the waveform.
Really the phonetic terms here are not actually relevant and have betrayed me. It's more that the 'k' sound is "more [ex]plosive" in that it seems to build up more pressure and turbulence (probably as you say, because the consonant is in the rear, so pressure builds and bounces around in the mouth more, whereas the "b" just mostly blasts out the front more quickly). And the "k" surely has a more peaky / spikey waveform in the audible range.
There's probably nicer programs that can do the same thing, aimed at people like musicians, but they won't have the phonetics-specific guides and help online.
There's also a large archive of speech recordings from a wide range of languages hosted by UCLA[1], which you can download and play around with. There might be newer archives now, but I remember this one, because Peter Ladefoged wrote the proverbial book on introductory phonetics.
Linguistics generally aligns quite pro-copyleft, so there will be a lot of freely available stuff online.
[0]: https://praat.org/ [1]: https://archive.phonetics.ucla.edu/