Excuse me, but it's a bad habit to introduce something with an acronym without saying what that acronym  stands for.  The site:  https://acronyms.thefreedictionary.com/CCR  lists 241 possible meanings for CCR. Which one is yours?

I assume, we are talking about ObjectScript? Then you got in the main method a <SYNTAX> error because "calling" is not a command keyword. So what are you really doing? We don't need the whole main method, the line with the call would be enough. By the way, a method name like "this_method" is not a valid name except if you place it in (double)quotes.  Something, which is formal correct, looks like this:

Method "this_MainMethod"()
{
    do ..SecondMethod()
}

Method SecondMethod()
{
    // ...
}

Your contribution is included too...

I just saw now, I published the next to last version instead of the last... sorry. I end up 53 bytes. This "s_0" was a work-around for not to use $g(z) by getting at least one loop for case, someone calls the method with an empty string

ClassMethod IsValid(s)
{
	f{s c=$a(s,$i(i))+1 ret:$i(z,c=42-(c=41))>0!'c 'z}
}

After I put all the solutions in a pot, salting them with some own ideas then filtering, I got a really nice solution with 55 bytes. Works for all the examples given by @Eduard Lebedyuk.

The best idea-donors where, among others, @Stuart.Strickland and @Lorenzo Scalese, thank you.

ClassMethod IsValid(s)
{
	f{s c=$a(s_0,$i(i))+1 ret:$i(z,c=42-(c=41))>0!'c 'z}
}

If my aging brain me do not misleads, you could save two more bytes

 g:"()"'[$c(c)  // instead of this (13 bytes)
 g:c=41-c+40    // use this        (11 bytes)
 

I hope, this change does not affect the way I use (some of the) mnemonics - am I right?

Class My.Mnemonics Extends %RegisteredObject
{
/// Set-/Reset mnemonic routine
ClassMethod SetMnemonics(rou={$zname}) [ ProcedureBlock = 0 ]
{
    set old=##class(%Device).GetMnemonicRoutine()
    use $i::"^"_rou
    quit old
    
MA(x)	write "This is MA "_x quit
MB()	write "This is MB" quit
}
}


// for example:
set old=##class(My.Mnemonics).SetMnemonics()
write /ma(123)
do ##class(MyMnemonics).SetMnemonics(old)

It seems, that will be hard to underbid...  Congratulations!

OK, one can short down those 20 bytes into 17 and we end up with 64 bytes.

ClassMethod IsValid(x)
{
1	s z=x,x=$replace($tr(x,$tr(x,"()")),"()","") g 1:x'=z q x=""
}

Again, speed wasn't asked

OK, I start with 47 chars... unfortunately, I have to add 20 chars more for that (stupid) extra requirement of ignoring characters like {, [, <, etc. therefore end up with 67 chars

ClassMethod IsHalfValid(x)
{
1	s z=x,x=$replace(x,"()","") g 1:x'=z q x=""
}

ClassMethod IsFullValid(x)
{
1	s z=x,x=$replace($zstrip(x,"*e",,"()"),"()","") g 1:x'=z q x=""
}

Speed was'n asked...

In the mean time the answer is already given by Mr Maslennikov and others, but to shorten your runtime,  you could also try a "variablenless" loop, maybe this gives you some seconds more... The emphasis is on "maybe".

// if you have null-subscripts enabled
if $d(^YYY(""))!1 for i=0:1 {quit:$order(@$zr)=""} write i

// if null-subscripts are not enabled
if $d(^YYY(-9E18))!1 for i=0:1 {quit:$order(@$zr)=""} write i

// of course, you can do that on any arbitrary level too
if $d(^YYY(1,2,3,""))!1 for i=0:1 {...} write i

// the value of -9E19 ist just for explanation, use a value suitable for your needs

May I ask for the background, why do you need that node count? 

Yes, accepts a file too, but as the following test shows, it does not make any difference... a parsing error remains parsing error

USER>set fn="/tmp/mytest.json"

USER>open fn:"nw":1 if $test { use fn write "[0.1, .2]",! close fn write "OK" } else { write "Houston, we have..." }
OK
USER>write {}.%FromJSON(fn)

<THROW>%FromJSON+38^%Library.DynamicAbstractObject.1 *%Exception.General Parsing error 3 Line 1 Offset 7
USER 2e1>

So where is that forgiving Cache/IRIS version?

Do you have a code snippet for us? Something like

write mylist.%IsA("%ListOfDataTypes") --> 1
set item = mylist.%GetAt(2)
//
// Now the big question: what do you (want to) do with this item?
//
// do you try to lock a global: lock ^myGlobal(item) ?
// do you try to open (a possible locked) Object: set obj=##class(some.class).%OpenId(item [,4]) ?
// something else?

May I ask, which Cache or IRIS version you use?

USER>write $zv
IRIS for UNIX (Ubuntu Server LTS for x86-64) 2021.2 (Build 649U) Thu Jan 20 2022 08:49:51 EST
USER>write ##class(%DynamicAbstractObject).%FromJSON("[0.1, .2]")

<THROW>%FromJSON+38^%Library.DynamicAbstractObject.1 *%Exception.General Parsing error 3 Line 1 Offset 7
USER 2e1>

As you see, my IRIS is by far not so forgiving... ☹

Nice, now we know nearly everything, except the most important info: what is the content of pField?

I assume, pObject contains the above JSON, i.e.

set pObject = {"priority": "2",
               "lastmodifieduser": "PORTAL",
               "assignedto": "jdoe01 STAFF",
               ...
               }