Hi!
There are of course two sides to this.
- The site you are importing data into
- The site you are importing from
In your case, it sounds like you control both which is great.
Within the destination site, you could modify the Import Limit Type setting to limit not by date range but by number of events: instead of being limited to 3 months in the future, you could set something appropriately high such as 4000 events. If that doesn’t work in your case, let me know: there are some (advanced level) workarounds we might be able to offer.
The other piece of course is the site you are importing from (the source of the data). To protect this site, The Events Calendar limits the number of events it will offer up for export to 50 – however it is entirely possible to modify this. Please see the following support topic to learn how:
theeventscalendar.com/support/forums/topic/events-api-not-returning-all-results
Does that help? Please do let me know if I can clarify anything else.