I can't reproduce your problem.
Form page = "
:test"
======Test======
<form>
Action template templates:testtpl "test:##RecordNumber##"
Number "RecordNumber" >0 ++ 0000
Textbox "Something"
Submit "Create a new record"
Thanks "[[test|Show updated tables]]"
</form>
Template = "
templates:testtpl"
======@PAGE@======
---- dataentry ----
Type : test
something : @@something@@
----
[<>]
If I enter
&*()-+@!~`1][{}|\:;"'?/ into the something field it works fine.
Created page record = "
test:0000"
======0000======
---- dataentry ----
Type : test
something : &*()-+@!~`1][{}|\:;"'?/
----
[<>]