More than one possible agreement
Pagat discusses versions with skip, reverse and draw effects, and notes that groups change their assignments. Use a complete rule list rather than assuming that an effect belongs to the same rank everywhere.
Write the agreement down
Record each special rank, its effect, any stacking condition and what happens at the end of a round. Check that everyone means the same thing before play. A shared note is more useful than resolving a difference only after the disputed card is played.
Tool scope
Our Bicycle-basic checker has no skip, reverse, draw penalty or stacking state. Do not use its answer to override an active penalty in another version.