Some buyer stakeholders are more open to pure Kanban and flow. Some buyer stakeholders prefer to pretend that the plan, that included significant guessing, is now written in stone. These types of organizations focus a lot on accounting for variances from the plan.
Saying you did not know enough about the situation early on when the plan was made is not generally considered an acceptable rationale for a variance in these organizations.
So, you may have to account for how many hours and monetary units (dollars, euros, etc.) that the team is off from what was expected and explain why that is.
If the person with the pay rate you had intended was not available and you had to use a higher paid person instead, your monetary unit variance will be off due to the usage of this higher paid person.
If your instructional/LX designer gets jury duty, you may end up explaining why you had a variance against the schedule.
Some stakeholders spend much time and energy doing this type of comparison on a monthly basis. Some do it quarterly. Some do it annually. Where possible, lean this process.
Lean-Agile will not help you with plan-driven processes and control mechanisms. Assess how much this will impact the team and who will have the role of collecting and reporting this information.