There are a few other issues with types:

1. I would expect types to be declared for event params. For example, I have to declare my own type for legendselectchanged event params passed into the event's callback function:

export type LegendSelectChangedEventParams = {
  // The `name` of the toggled series.
  name: string;
  // A map of series name to selection status (for all series).
  selected: {
    [name: string]: boolean;
  };
  type: 'legendselectchanged';
};

But when using this type like so:

const onLegendSelectChanged = useCallback((params: LegendSelectChangedEventParams) => {
    console.log(params);
  }, []);

useEffect(() => {
    const chart = chartApiRef.current;
    if (!chart) return;

    chart.on('legendselectchanged', onLegendSelectChanged);
    return () => {
      chart.off('legendselectchanged', onLegendSelectChanged);
    };
  }, [chartApiRef, onLegendSelectChanged]);

I would then get a TS error anyway:

Argument of type '(params: LegendSelectChangedEventParams) => void' is not assignable to parameter of type 'WithThisType<(...args: unknown[]) => boolean | void, EChartsType>'.
  Types of parameters 'params' and 'args' are incompatible.
    Type 'unknown' is not assignable to type 'LegendSelectChangedEventParams'.ts(2345)
const onLegendSelectChanged: (params: LegendSelectChangedEventParams) => void

Where the ...args: unknown[] part is coming from here:

declare type ECEventDefinition = {
    [key in ZRElementEventName]: EventCallbackSingleParam<ECElementEvent>;
} & {
    rendered: EventCallbackSingleParam<RenderedEventParam>;
    finished: () => void | boolean;
} & {
    [key: string]: (...args: unknown[]) => void | boolean;
};

1. There are some typos in type names:

// typo: should be RegionOptions
interface RegoinOption extends GeoStateOption, StatesOptionMixin<GeoStateOption, StatesMixinBase> {
    name?: string;
    selected?: boolean;
    tooltip?: CommonTooltipOption<GeoTooltipFormatterParams>;
}

interface GeoOption extends ComponentOption, BoxLayoutOptionMixin, AnimationOptionMixin, GeoCommonOptionMixin, StatesOptionMixin<GeoStateOption, StatesMixinBase>, GeoStateOption {
    mainType?: 'geo';
    show?: boolean;
    silent?: boolean;
    regions?: RegoinOption[]; // typo: should be RegionOptions
    stateAnimation?: AnimationOptionMixin;
    selectedMode?: 'single' | 'multiple' | boolean;
    selectedMap?: Dictionary<boolean>;
    tooltip?: CommonTooltipOption<GeoTooltipFormatterParams>;
}

yes yes yes!!!!!!!!