[GAMEPLAY] Runaan's Bugged Interaction with Kog'Maw W?

As seen in the video (posted on Reddit), Kog'Maw's autoattack target is Ezreal, but Runaan's bolts fire at Ahri and Janna, who are at like 60-degree angles to Ez (with respect to Kog). I thought Runaan's was supposed to fire only at units nearby the primary attack target, and there's no way that both Ahri and Janna are "nearby" Ez. I've only seen this weird spreading of the bolts when Kog'Maw is attacking with W active, but that could possibly be only because of the range making it noticeable (even that's not likely, since I haven't seen it on Jinx or Trist or Cait). Also this exacerbates how OP Kog'Maw is right now...

Reproduction steps:

1. Play Kog'Maw.
2. Buy Runaan's.
3. Autoattack someone with W active, with others not "nearby" but within autoattack range.

By the way, I have been curious--since the preseason patch--about the changed functionality of Runaan's, aside from this bug. In particular, before preseason (that is, before Runaan's was reworked), it could fire at targets normally outside of the user's autoattack range, as long as they were "nearby" an actual autoattack target who was within range. I believe this was even confirmed by a Rioter as intended. However, with the new Runaan's, this is no longer the case. Even with the recent tweak of calculating distance from hitbox edges, the basic functionality is different from before. This was not documented in patch notes and is not even noted in the LoL wiki, and I'd like confirmation that it was consciously changed behavior, rather than something that slipped under the radar.

Thanks a lot!

EDIT: This seems to happen with Ashe Q active, as well. Perhaps there's something to do with AAs that are modified for a duration?