19.2The biggest question is not “what maps to what?”

It's:

What are the business semantics of this data?

For each important field, ask:

What does this field actually mean?

Who owns it?

Who is allowed to change it?

Is Salesforce the source of truth
or only a consumer?

What does missing mean?

What does null mean?

Can the value be overwritten?

What identifies the entity uniquely?

Can that identifier ever change?

These questions uncover far more defects than discussing column names.