Hard questions

I can only speculate.
The water to the right is a trench in which the old lighthouseboat is rotting away. Behind it is some land and a dike, then the Suriname river. The Commewijne is hundreds meters behind the back of the photographer.
The bunker features with all gun emplacements, see also the 6-inch. There are more such bunkers around and now that I look at it: it could also be a mg/at bunker. Note the firing port.
Also note that a bunker features in the wartime picture of the big gun. Was it ammo storage?
Our gundeck was renamed people's theater in 1982. We can only speculate how much work was done to change it for that purpose. Note the raised front portion is possibly hollow, because of the tree growing through it. A 25 year old tree could easily do this in Surinam, I have seen worse cases of nature taking over men's work in a few years.
Note also that on the wartime picture of the big gun the concrete centre is surrounded by a brick section. These are missing in the 6-inch gundecks these days. It could be that the bricks were taken away for other use or that some builder used them in the surrounding Javanese kampong. You will see several old guns in the neighbours gardens if you stroll through the kampong.