Can’t find anything.
The only mentions about AoE size I can find are not falcon, but musket:
3 March 2016:
[Musketeer]
Musketeer’s [Snipe] hitbox being abnormally different to the crosshair targeting image has been corrected.
- ‘Snipe’ skill having an unusually large hit box has been fixed.
And
18 August 2016:
Musketeer:
- Snipe:
- The Scopes hitbox has been made larger.
I will put all falcon notes here:
18 August 2016 hotfix 2: [First Strike] Fixed the occasional delay that occurred with this skill.
18 August 2016: [Sonic Strike] Fixed issue where Blind sometimes wouldn’t apply.
18 August 2016: [General Change] Falconer abilities are now available whilst riding a companion.
28 April 2016: Falconer [Sonic Strike: Confusion] Attribute has been added.
- Targets in line of fire from Sonic Strike will be
afflicted with [Blind], Afflicts the enemy with [Sonic Strike:
Confusion] debuff for 3 seconds.
- [Sonic Strike : Confusion]: Reduces Psychical Defense by 15% Per Attribute level, Increases physical damage by 2% Per Attribute level.
21 April 2016: Blistering Thrash
- 30% Chance to afflict the enemy with [Blind] when attacking.
18 February 2016
► Hanging Shot:
○ If you swap weapon whilst you are under the hanging shot effect, the skill effect will immediately cancel.
When swapping to a Musket weapon, Hanging shot will immediately cancel.
○ During Hanging shot you will not be allowed swap to a musket weapon.
For 2-Handed bows with Hanging Shot, Changing to 1-Handed Bow is still possible.
21 January 2016
► Hanging shot:
○ Now allows the user to use the Quarrel Shooter ‘Running Shot’ skill whilst flying.
► Call:
○ ‘Call: Obtain’ attribute has been modified so that potions obtained via this skill have a resale value of 0.
Using gwenyth’s patchnote pastebin, nothing was found either.