Is it possible to understand was the field trained or not?
The processing log can be very informative in the meaning of what fields of the invoice were trained by the verification operator or administrator and what fields were extracted as-is.
Please take a look at the screenshot:
The record The field %fieldname% was chosen from a FlexiLayour variant means that the location of this field was corrected by someone. So, this correction participated in the generated by training FlexiLayout.