S
Sunseeker
Guest
The first rule of gaming: If a rule does not significantly impact balance, and the rule is reducing the fun, the rule should be altered to make more fun possible.
Some players might think it is fun to give their characters a challenge in spellcasting - their characters can only cast a spell they have seen cast is a wonderfully fun quirk!
Others might turn an angry glare at a DM that told them they can't cast a spell unless they see it cast.
If I had a Kenkyu player, I'd allow suggest they bypass this rule by allowing them to use a minor illusion, thaumaturgy, or other easy method to create the sounds of the spell once and then copy it in the future.
I would agree that with a flavor element like "you can only mimic what you've seen" if a player finds that an engaging element of play, then more power to them. If a player just wants to play a crow-styles scavenger without that entirely fluff element, go for it.