Larson Kohl's Wikipedia page does state that he found human ancestral remains, but it was Australopithecus afarensis (the same species as the famous Lucy) but nothing about giants.
The place described at the passage is Mumba Cave, which is located on the shore Lake Eyasi (not Elyasi) in Tanzania and was excavated by Kohl and his wife margit in the 1930s. The findings in the cave, by Kohl and his wife, and by later archaeologists are described in this Indiana University Article and it doesn't say anything even remotely close to giants.
There are also published scientific articles regarding Mumba cave, none of them depicts giants. Google Scholar results for Mumba Cave
The quote that is attributed to Dr. Louis Burkhalter was not said regarding the supposed findings of Larson Kohl, but on other findings, that didn't include skeletons or any other human (or other creature) remains at all:
He is also notable in some fringe circles for suggesting the existence of giants as a "scientific fact" in the Acheulean period when commenting on the gigantic lithic finds of Denis Saurat at Sasnych in Syria. Later review of his suggestion notes that large lithics found could have been used for stunning and traps and present no evidence for giant populations.
Wikipedia sources the quote to a french book by Burkhalter himself:
Burkhalter, Louis., "Bibliographie préhistorique (suite et fin)" in Bulletin du Musée de Beyrouth. Tome IX, 1949-1950
And the rebatle to him is sourced to a french article:
Edeine, Bernard., Monuments mégalithiques détruits ou en voie de disparition dans le bac de Caux, Annales de Normandie, 1957