A CUBAN MALLET?
The German firm of Orenstein & Koppel built many narrow-gauge Mallet locomotives, but only six were exported to North America. One was sent to Cuba and the other five ended up in Mexico.
The loco clearly O&K b.n. 1645, built in 1905. This was an 0-4-4-0 Mallet, 150 hp, and 29.92 in. (760 mm) gauge.

It ran at Confluente sugar mill in the 1900-1909 era. This mill was situated at the western edge of Guantanamo city, and has long since gone-certainly by 1937. It operated 1902-7 but did not grind in 1908 although that does not mean it did not operate later.

The mill was very small and had a capacity at the very lowest of output range. It is not one of the other two you mention, although its cane areas may have been absorbed by them-including its rail lines-regauged if necessary.

A nonstandard loco with articulation in the land of the Baldwin is not likely to have survived today.

Anybody have anything else about this beast?