although Legend Items can be hacked, the bigger problem is when Eternal Items are hacked. that is because Eternal Items are stronger than Legend Items, and many Crystals can’t be used on Eternal Items, which makes it easier to tell when they are hacked. the easiest way is to compare the suspected items to the Items listed in the Eternal section of the LegendEx, and the somewhat harder way is to know which Crystals can’t be used and then compare, and most difficult, memorize the Eternal LegendEx.
there are some Resource Systems, and some high defense Builds, that can make it look like HP/MP isn’t fluctuating. on the other hand, if after doing any research that it is possible for you to do, if you still think there is a hack being used, then go ahead and report it, and the Dev’s will check it out.
if you think there is a bug to report, go to the Bug Reports Thread or use the Bug Report Header when you make a new post.
the ??? is usually only for Players who are in Eternal League, but then there are some Players who share their Builds that have gotten them into Eternal League.