Buy up Charging Boar from frequency 2 to frequency 3 (level 3->4) for 8 EPs. (The schtick is listed as “Wounded”, so I’m not sure if there’s something that restricts that. This may not be the most efficient use of 8 Eps, since I’m not sure you actually use it very often, so if there’s another level 4 schtick you can buy, you might want that instead.) Buy up Falcon’s Dive from Frequency 4->5 (level 4->5) for 6 EPs. Buy up Crane’s Force from Frequency 5 to Frequency 6 for 6 Eps (level 5->6).
20 EPs total, and it will keep your pyramid balanced.
Also, you should spend 3 more Eps to increase Swallow’s Flight from Frequency 5 to Frequency 6. Combined with Shoot Twice, and increasing Crane’s Force to frequency 6 and Falcon’s Dive to Frequency 5, this means that in every action you want to attack, you get:
One pool of 28 Archery dice (normal base dice, doubled). You could split this against two targets for 17 dice (because of the +3) each. One pool of 14 Archery dice (Shoot Twice dice). +3 dice means 17 dice, or you can split this pool as well (I assume), for 10 dice each against two other targets.
At x5 damage, this will rate you about 75 damage against each of two targets and 45 damage against two other targets. Or 75 damage against three targets, or 100 damage on one and 75 on another, etc. etc. You probably want about 10 more levels of Longbow skill as well, to maximize your expected damage when you’re rolling all 28 dice against a single target.
Note that more copies of Swallow’s Flight, at frequency 6, will help the more you split your dice. You’ll need to buy more level 2 schticks before you can buy another copy of Swallow’s Flight, though.
Once you have bonus dice schticks, it’s almost always worthwhile to split your dice, even if it’s just “all but one die on the primary target, and one die (plus bonuses) on a secondary target”. Either the secondary target is forced to dodge, or you do them some amount of damage; over time, that will add up. In your case, if you have a +3 die schtick and a doubling schtick at frequency 6, you can do even better— your double dice schtick gives you a pool of 28 dice, which you can split into attacks of 25 dice and 3 dice. Both of those then get the +3 die bonus, for 28 dice and 6 dice. This maximizes the damage against one target (without exceeding the stat doubling cap) while also doing ~6 successes to a secondary target. If you had a second Swallow’s Flight, you could make that 28 dice and 12 dice. Etc.
Two attacks per action, one with doubled dice.
Try to have 3 targets. If so:
Split the attack with doubled dice 22 and 6. Add 3 dice for bow and 3 dice for Swallow's Flight to get 28 and 12.
Use the other 14 dice on a third target.