I am pretty sure that syntaxically is not a real word and is probably a misspelled form of "synactically". However, for what its worth, you guys do a better job with English than many people I know here in the US. :-)
Here's what dictonary.com says:
with respect to syntax; "syntactically ill-formed"
Stefan Zoerner wrote:
> Ole Ersoy wrote:
>> Attribute value 'http://example.com/users/accounts/L0' for attribute
>> 'm-supObjectClass' is syntaxically incorrect
>> Should it be "Syntactically"?
> I am not a native speaker. But the word "syntaxically" seems to exist, I
> am not sure, whether syntactically is something different.
> Here is a text, which uses syntaxically:
> Perhaps, one of our native speakers can comment on this.
> Greetings from Hamburg,