I checked out that plugin, I don't actually have it as it turns out but on their page they say its compatible with Heli Signals.
The issue is the dev of that plugin is returning from "ShouldFancyDrop" as if it were a Boolean hook, so they are returning false, which some argue is more logical because we don't want Fancy Drop to act on those signals. However, the hook isn't Boolean and it is much more widely accepted that when returning a hook that requires a non null return value to stop normal behaviour, you should return true (which I do). This was discussed at length in the Oxide/Umod discord a long time ago and this was what was decided.
In this case it doesn't hurt anything or break any actions, it just causes the console info spam you are seeing and will continue to do so unless one of us changes the returned hook value. As I'm using the most widely accepted way of returning this type of hook, so I won't change, as this will then cause conflict with many more plugins. This is the same as the console spam that so many servers see with Stack Modifier plugin, as he refuses to return from "CanCombineDroppedItem" hook in the already accepted way as 99.9% of every other dev out there as I described above!
Anyway, it's up to you, you could find that hook in his code and change the return value to true instead of false, or just ignore it (or ask him to change it for the reasons explained )
Z