The generators in the mod have a priority lower than every other power generation structure in the game, even lower than accumulators. They will produce at full power only if all other power production is insufficient and all other energy storage is drained, making them nearly useless and causing various undesirable behaviors in the electrical network. A generator capable of producing power forever without fuel should be prioritized above everything else. Also, the internal reservoir of the reactor that is presumably meant to act like an accumulator does not drain to power your grid under any circumstances.
I was able to fix it by changing usage_priority of the three generators in demo-crash-site.lua from "tertiary" to "primary-output". While the capacity still doesn't function it no longer causes issues with the Accumulator charge bar in the Electric network info panel, and they don't really need to function like accumulators.
(Small nitpick: the pictures in the mod description don't show the updated generator numbers)

I'm glad someone noticed this as well. I was doing some testing and was wondering why they would rarely have any electrical output at all when all my other power generators were running at full blast.

Til I noticed it had such a low priority it made them basically useless. And was going to post asking why they weren't consider more like a solar panel, as it costs no resources to generate power and should always be used over others. I was going to suggest your changes as well. So with the 'fixes', they now operate much more reasonable.