Originally Posted by
Trenloe
The effect with fortune in the text is purely a reminder that Sure Strike uses the Fortune trait, and so has some limits regarding other fortune effects. As has been mentioned, abilities with the "Fortune" trait can have different dice rolling mechanics associated with them, and therefore there are no specific mechanics associated with this trait within FG.
Additionally, Sure Strike is not just limited to roll 2d20 and keep the best, it also ignores circumstance penalties and the flat check for concealed/hidden. Concealed/Hidden can be handled with the IGNORECONC and HIDDENDC: 0 effects, but ignoring circumstance penalties cannot be automated at this stage.
We will, at some point, add in a form of roll 2 dice and keep the best/worst, but it's not high on our priority list. FYI - this type of functionality isn't implemented in the PF1e ruleset - you may be getting confused with the CA and GRANTCA effects which are a hangover from the D&D 4e ruleset, and provides the flat-footed condition.