Make a checkbox that is used on 2 sheets show the same value.

Can you please clarify whether there will only ever be one cell checked/unchecked on each sheet or will you have multiple rows that could be checked/unchecked and matched up across the sheets? If it's just one cell, why not use a direct cell link instead of a formula?

If you have access to the Data Mesh premium app, you can use that to sync the checkboxes.

If you don't have access to it, then give the INDEX/MATCH function a try. Create a helper column in each sheet to return the checkbox value from the other sheet like so:

in schedule:

=INDEX({checkbox column from tracker},MATCH([Task Name]@row,{task name column from tracker},0))

in tracker:

=INDEX({checkbox column from schedule},MATCH([Task Name]@row,{task name column from schedule},0))

This will look for a match to the task name in the other sheet and return the associated checkbox value.

From there, you'll create an Automation in each sheet to check/uncheck the checkbox based changes to the value of the MATCH/INDEX result. For instance, if Task A in the tracker changes to 'checked' then the INDEX/MATCH value on the schedule will update to checked so you can have an automation that listens for changes to the INDEX/MATCH helper column and either checks or unchecks the box in the schedule based on a condition.