I just read through the 2018 FIG, and it is amazing to me how inconsistent the reporting requirements are between data points.
For some data points, if the field doesn't apply to the loan, you might have to report "NA", some require a code that means "NA", or some just leave the field blank.
Rounding is going to be another issue, as certain fields are rounded to two places, three places, or for DTI and LTV, it depends on how your institution rounds the field in their decision making (rounded to the nearest whole percentage or not), and other fields don't specify how rounding should occur (loan amount).
The actual data points aren't going to be the hardest part of this regulation. It all this technical BS that is going to trip people up. Why not round all dollar or percentage fields to two places and require "NA" for all fields that aren't applicable.
All opinions are my own, not my employer's