Suppose we have two items. First one contains quoted/unquoted parameters in the key.
Second item is a calculated item for the first one.
count() function is used.

(1) Server
a)
When the key is:
logrt[/tmp/test.log,some words]
formula is:
count("logrt[/tmp/test.log,some words]",60)
Then all is fine, both items are working good.

b)
But if the key is:
logrt[/tmp/test.log,"some words"]
and formula is:
count("logrt[/tmp/test.log,"some words"]",60)

Then calculated item becomes notsupported and I see error text for the item:
Invalid first parameter in function [count("logrt[/tmp/test.log,"some words"]",60)]

c)
Next case is even more scary.The key and formula:
logrt["/tmp/test.log","some words"]
count(logrt["/tmp/test.log","some words"],60)

Calculated item becomes notsupported and error text is:
Cannot evaluate function [count("some words"],60)]: item [it0:logrt["/tmp/test.log"] not found

(2) Documentatiion
Note for documentation: for most of the functions first parameter is required but not the optional as described in the documentation.
Without ",60" as parameter for formula the calculated item will nor work ( b) case as example).
I'm sure that documentation should be improved.