Is there a method to restrict the use of special characters other than "space, (), [], and <>"

You can try this :

a!localVariables(
local!allspecialCharacters: "`!@#$%^&*-_={}|\/:;'"",.?",
local!textField: "",
a!textField(
label: "Text",
labelPosition: "ABOVE",
value: local!textField,
saveInto: { local!textField },
refreshAfter: "UNFOCUS",
validations: {
if(
len(local!textField) = 0,
null,
if(
len(local!textField) > len(
stripwith(
local!textField,
local!allspecialCharacters
)
),
"Special Characters not allowed",
null
)
)
}
)
)

You can try this :

a!localVariables(
local!allspecialCharacters: "`!@#$%^&*-_={}|\/:;'"",.?",
local!textField: "",
a!textField(
label: "Text",
labelPosition: "ABOVE",
value: local!textField,
saveInto: { local!textField },
refreshAfter: "UNFOCUS",
validations: {
if(
len(local!textField) = 0,
null,
if(
len(local!textField) > len(
stripwith(
local!textField,
local!allspecialCharacters
)
),
"Special Characters not allowed",
null
)
)
}
)
)

Thank you.

I kind of made it like 

a!isNullOrEmpty(
  concat(
    a!forEach(
      items: {
        "`","~","!","@","#","$","%","^","&","*","_","-","=","/","?","{","}",";",":"
      },
      expression: {
        if(
          search(fv!item, ri!textField, 1) = 0,
          {},
          1
        )
      }
    ),
  )
)

but, think yours is better.