I can say that the Next Actions F/C/R values may differ from the values of the custom stats.
Hand2Note calculates the values of Next player's actions FCR based solely on the following player actions, i.e. It does not take into account that the same action can be taken in different spots.
For example, when you make CBet on Flop, your next action may be Fold on raise, but also Fold on Turn Donk. Both situations will be considered in the same F value of Next player's actions.
Therefore, in the Hand2Note statistics, Next player's actions FCR has some inaccuracy, especially when playing in positions on opponents.