Here I have uploaded 1) a spectrogram of a typical call, 2) a clip of a single call, and 3 - 9) the raw recording that I took of a single male calling in his pool.
Notes: Despite there being multiple pools at the type locality, and having found an abundance of adults at the same site previously, only 3 males were heard calling on each night (13 and 14 June). The three males were spread out within boulder complex, probably at around 10-30 m from each other and always in different pools. All of this was after heavy rain in the days and hours preceding.

I would appreciate if anyone has any theories as to what triggers breeding for this species, that is assuming they form aggregations like other Caco species

Description from the paper

A total of 20 calls from the holotype specimen (PEM A15391) were recorded at the type
locality over a period of 18.5 minutes. Air temperature during this time was 10º C. The call of C. cederbergense sp.
nov. can be described as a short, pulsed bray emitted singly at long intervals (58.3 ± 97.23 s, Fig. 9a, Table 3). It has
a mean dominant frequency of 1.8 ± 0.03 kHz, and a dominant frequency range of 0.92 kHz. Calls have between
18 and 26 pulses at a rate of 90.6 ± 7.35 pulses per second. No territorial call was heard, but no more than a single
male was heard calling in a pool at the Type Locality.

Cacosternum cederbergense Cederberg Dainty Frog or Cederberg Caco. From Cederberg, Western Cape. https://www.tyroneping.co.za/amphibians-of-southern-africa/cacosternum-cederbergense-cederberg-dainty-frog-or-cederberg-cac0/

Nearly Legless Skink

Little skink with spindly back legs and tiny front legs. Found underneath a stone, it moved about in a snake-like fashion with its front legs always held against its side. The back legs were only used occasionally and especially for small or slower motions.