In 1932 positron and annihilation were discovered, but in 1928 Dirac had provided a formula allowing for the positron
Did anyone between that date and the discovery of electron ever imagine or suggest of antimatter or a positive electron. How did they interpret the electron?
Not quite as specific as what you're looking for, but searching google-books using the phase "positive electron" for 1800-1931 gives several pages of hits. Most of these use the phrase in connection with atomic nuclei (or with alpha particles, prior to Rutherford's famous scattering experiment), but some appear to involve speculation about the existence of a positively charged analog of the electron, such the following two. I don't have any more details about the 1928 reference because this journal does not seem to be freely available on the internet. However, the journal can probably be found in most major U.S. universities (e.g. all print volumes from 1861 are at The University of Iowa). I tried adding "Dirac" to the search results, and two or three things looked promising, but none seemed to be freely available, and thus I'll leave it to you or others to pursue further.
Ernest Rutherford, Present problems in radioactivity (also here), Popular Science Monthly 67 [#1] (May 1905), 6-34.
(from bottom of p. 9) ... no evidence has been obtained of the existence of a positive electron corresponding to the negative electron.
The Chemical News and Journal of Industrial Science 136 (1928) (also here)
(from p. 194) Let us, for instance, picture a true equivalent to the negative electron---a positive electron of the same infinitesimal atomic weight. Then if ...
Newton had already discussed the possibility of repulsive forces between particles. This was obviously a long time before the discovery of electricity so it wasn't phrased in terms of positive and negatively charged particles. But the kernel of the idea was there.
I want to add, that Aristotle (which obviously Newton had read), had noted that all ancient philosophers were agreed that principles are contraries, that is they come as opposites. This might have a bearing on the above physically grounded speculation y Newton.
The term antimatter was first used by Arthur Schuster in two rather whimsical letters to Nature in 1898,[13] in which he coined the term. He hypothesized antiatoms, as well as whole antimatter solar systems, and discussed the possibility of matter and antimatter annihilating each other.
https://english.stackexchange.com/questions/15994/when-was-antimatter-first-used
The idea of antimatter seems to have been part of the ancient secret canon that Newton, Kepler and others were privy to:
Viktor Schauberger; The Repulsine, UFO's and Flying Saucers of Nazi Germany
It was nearly the end of WWII. At that same time, scientist Viktor Schauberger worked on a secret project. Johannes Kepler, whose ideas Schauberger followed, had knowledge of the secret teachings of Pythagoras that had been adopted and kept secret. It was the knowledge of Implosion (in this case the utilization of the potential of the inner worlds in the outer world). Hitler knew - as did the Thule and Vril people - that the divine principle was always constructive. A technology however that is based on explosion and therefore is destructive runs against the divine principle. Thus they wanted to create a technology based on Implosion. Schauberger's theory of oscillation (principle of the overtone sequence, monochord) takes up the knowledge of Implosion. To put it simply: Implosion instead of Explosion! Following the energy paths of the monochord and the implosion technology one reaches the realm of antimatter and thus the cancellation of gravity.
Van Helsing, E. S., & Canaria, G. (1995). Secret Societies and Their Power in the 20th Century.
Schauberger's theory is also claimed by others to have had connections with the ancient Vimanas and Sumerian legends of antimatter and implosion that the Nazis were working on.
"German UFO literature very often conforms largely to documented history on the following points: ... Nazi Germany conducted research into advanced propulsion technology, ... Viktor Schauberger's engine research, ...." https://en.wikipedia.org/wiki/Nazi_UFOs
"This article deals with a military black project. Because of the nature of such projects, the most authoritative sources (any involved governments and defense contractors) may not even acknowledge its existence. The most reliable sources may be highly speculative." https://en.wikipedia.org/wiki/Talk:Nazi_UFOs
Third Reich Operation UFO Nazi Base In Antarctica Complete Documentary
"Trustworthy, authentic information about Viktor Schauberger directly from primary sources. .... The sharing of this information and knowledge is supported by the PKS Organisation (Pythagoras Kepler System according to Viktor and Walter Schauberger)." http://pks.or.at/en/
"Implosion is no invention in the conventional sense, but rather the renaissance of ancient knowledge, lost over the course of time." Implosion Magazine, No. 83, p. 16 in Callum Coats: Energy Evolution, 2000. "You must learn to think one octave higher. Only then will you learn how implosion energy works." Implosion Magazine, No. 83, p. 27 in Callum Coats: Energy Evolution, 2000. https://en.wikiquote.org/wiki/Viktor_Schauberger
The implosive forces in Schauberger's turbines were compared to those found in tornadoes and hurricanes.
Fishman, Gerald J. "Positrons observed to originate from thunderstorms." Eos, Transactions American Geophysical Union 92.22 (2011): 185-186.
Castelvecchi, Davide. "Rogue antimatter found in thunderclouds." Nature News 521.7551 (2015): 135.
Bowers, G. S., et al. "A Terrestrial Gamma‐Ray Flash inside the Eyewall of Hurricane Patricia." Journal of Geophysical Research: Atmospheres 123.10 (2018): 4977-4987. "We report the first observation of gamma‐ray emission from lightning within a hurricane eyewall, consistent with production by a downward beam of positrons."
