My understanding is that flags are set to 0 if false and 1 if true, am I missing something? Specifically for the Ice Devil 3 of its saving throw flags are set to 3.
// 1 = First Entry Single Digit, 2 = First Entry Double Digit, 3 = Later Entry Single Digit, // 4 = Later Entry Double Digit, 5 = Negative BonusNot sure what that means, but it's just before the section that defines the various save_flag attributes. You may want to look at the code yourself: (https://github.com/Roll20/roll20-character-sheets/tree/master/5th%20Edition%20OGL%20by%20Roll20). See line 6783.