"Doesn't make any sense" is not the same thing as "doesn't match my assumptions". There is no reason to assume that one entity is at work in both of these locations, other than the one entity who we know is at work in both locations. Russia and Cuba have a long history of cooperation, but China and Cuba don't. Few in Cuba would want to piss off Russia by inviting in the Chinese for some goofy microwave project. China and Russia are also not the closest of allies. Just as the USA military-industrial complex is not a monolith, its symbionts abroad are not monoliths.

There is no reason to believe any particular thing we're told about these events. We should be extremely Bayesian, paying attention only to things we know: both phenomena affected USA diplomats, USA has routinely experimented on and otherwise disregarded the safety of those serving abroad, descriptions of symptoms are provided on the record while wide-ranging speculation is given anonymously, etc.