There is no incorrect information on that page aside from skill names needing updating to their new version, although it could probably stand a reorganization and editing out of the extraneous stuff like what it used to do and when it changed.

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I specifically tested that before I posted last night with a brand new Bard who literally joined the guild then ran and screamed at rats. It works. You must be using the wrong syntax or something.

>sw
You go southwest.
[Barana's Shipyard, Lumber Storage]
Huge piles of wood teeter uneasily all about you. The smell of sawdust and the fresh green scent of raw wood is everywhere. A layer of wood shavings, scattered on the ground, shows numerous tiny tracks running in all directions. Nearby, a rickety old dock sags, a shabby barge tied up to it. At the opposite end of the wood-lot, a large kiln stands alone. You also see a ship's rat.
Obvious paths: northeast, southeast, south, southwest, northwest.
>scream havoc
You turn to face a ship's rat.
Opening yourself as the conduit to the rage of every innocent slain at the hands of the wicked before their time, you channel their fury into a single, prolonged shout directed at a ship's rat. A wave of sound lands a light hit on a ship's rat, driving it back a short distance.
Unable to keep its balance, a ship's rat tumbles to the the ground!
Roundtime: 3 sec.
[You're solidly balanced and in dominating position.]
>scream conc
****************************************************
* Please check NEWS NEXT for unread NEWS items. *
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>
Inhaling deeply, you focus your energy and unleash an ear-splitting shout directed at a ship's rat. The concussive blast lands a light hit against a ship's rat's right foreleg!
Roundtime: 1 sec.
[You're solidly balanced and in dominating position.]
>
The ship's rat climbs to its feet.
>exp
A ship's rat turns to face you, leaving Shadyth on its flank at pole range!
* Moving weakly, a ship's rat bites at you. You slap away little of the teeth with a tapered cutlass.
[You're solidly balanced and in dominating position.]
>

Circle: 1
Showing all skills with field experience.

SKILL: Rank/Percent towards next rank/Amount learning/Mindstate Fraction
Light Armor: 2 00% dabbling (1/34) Defending: 2 00% dabbling (1/34)
Parry Ability: 3 00% dabbling (1/34) Small Edged: 3 00% dabbling (1/34)
Melee Mastery: 3 00% dabbling (1/34) Evasion: 1 00% dabbling (1/34)
Performance: 4 05% dabbling (1/34) Bardic Lore: 4 15% considering (6/34)

Total Ranks Displayed: 22
Time Development Points: 576 Favors: 0 Deaths: 0 Departs: 0
Overall state of mind: clear
EXP HELP for more information
>

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Not that it's necessary, but I've just confirmed them too. Scream havoc and scream concussive are both available at 1. For the record, so is practice breathing.