Looks like a bunch of functions related to easily accomplishing testing more than functions to establish the structure and operation of a game.
Function in blueprint libraries exist primerly because there C++ equivalents can’t be bind direcly to blueprints or they invove something that blueprints don’t support nativly, prime example is math functions which are part of struct FMath and structs can’t have functions in blueprints so they need to be wrapped MathBlueprintLibrary, same goes with functions in FVector and FRotator.
In general it is ok to use them and they will work without any problem, but it really depends on case, some functions like GetAllActorsOfClass assuming you searching only for single one can be done a lot more preferment with breakable TActorIterator loop:
…instead of making massive array and searching it for single actor because blueprint don’t support iterators.
I think best answer is if you look up on source code of specific Blueprint Library and see how it is coded as it usally contains equivalent of C++ that you should normally use.