The set up for the scenario is promising enough, and you can definitely make some adaptations to make this a stronger session overall. There is a fair amount to re-write and adapt to make it work though.
The biggest issues come from a bunch of superfluous elements. There is a cast of strong characters, but some of them become non-leads for the players. I am struggling to understand what leap in logic the players would need to make to visit Cuba, as NOTHING points them there, and the character itself can be cut completely with zero consequence. The encounter at the train station seems entirely unrelated to the plot at hand as well, and seems to only serve as a thread to the next scenario rather than impacting the action at hand.
The material is salvagable, and there is some potential in the ideas of the scenario. It is just bloated in places, and looks like it was written as a scenario in the middle of a longer campaign that involved more story elements than what are mentioned.
The last thing that just tipped this into 2/5 is a spoiler.
The inclusion of a confirmed and official Judeo-Christian God is in really poor taste for a number of reasons. The least of which being the potential discord this could cause in a real life play group. The narrative implications and difficulties in implementing this as the actual focal point of the scenario and in a long standing contuity are staggering, and not in a good way. Let alone this can be quite at odds with the suggested tag of "Call of Cthulhu" on DTRPG.