Increased Warcry Buff Effect seemingly does nothing

Not sure if this mod is intended for warcries not yet added but it does not affect infernal cries dmg for empowered attacks, saw no difference in dmg ranges on hitting same boss and resetting at checkpoint for 0% inc effect and 60% effect respectively.

There are some stats migrated from PoE1 that has no use in PoE2. Warcries for example don't provide buffs in PoE2.

What are some other examples of that, other than weapon specific stuff for weapons not yet added. Every other mod on ruby jewels (only source of warcry buff effect atm) does something.

Link skill clusters, Echoing Pulse notable on the skill tree. Maybe something else I'm not aware of or don't remember.

Well link skill stuff is same as axes, daggers, etc. There are no link skills yet so whether those mods work can't be known. Warcries do exist though and the gain as fire mod on infernal in PoE 1 IS scaled by warcry buff effect. In Poe1 mods that scaled with enemy power were duration buffs and were separate from exert modifiers. In PoE2 they moved warcry effects directly onto just the exerted attacks for both infernal and seismic. Warcries likely worked the same way as PoE1 initially before getting reworked, like many other systems have been like curses and triggers, and buff effect mod was just missed.