Trophy collector should increase ability range by 1% with each stack but it doesnt change at atkk, doesnt matter if you have 0 or max stacks abilities still have the same range. All the other bonuses from item works just fine (souls, HP, sprint speed).
This is also bugged for Cultist Sacrifice and Arcane Surge. Neither of those shows an increase in the actual cast range value of abilities or active items, but the increased range effect does appear to work as intended. So clearly seems to be somewhat buggy in the UI aspect of displaying the accurate range of things but will still have the (seemingly) proper value. Also seems to be specifically an issue with conditional range increases, since all three of these items are flawed in this way.