If anyone is wondering about how to prepare or negotiate Disneyland in the rain, here’s a blog about that: https://www.magicalmousetours.com/single-post/2019/02/02/What-to-expect-and-plan-for-a-wetrainy-day-at-Disneyland
This one adds child specific ideas: https://www.magicalmousetours.com/single-post/2019/02/03/What-you-need-to-know-to-navigate-Disneyland-in-the-rain-with-small-children
If anyone has other ideas, add them to the comments.