Perhaps a shift in mindset about how to approach using Svelte would help. Svelte is not React, and using React for an extended period really changes how you think about frontend code (structure-wise etc).

As a quick example, the Svelte 'ecosystem' is simply the Javascript ecosystem, which existed well before React. You can import any npm module to a Svelte app. Outside of the React-specific packages (which I argue are overkill), such as Redux or Redux-enabled form libraries, what are you missing? Pre-styled components like calendars, modals, popups, are available in a range of vanilla-JS packages. Anything more than that and it's possible that React thinking has over-complicated your approach.