Yeah, T is definitely better, thinking about it.
I would hope if it was a fill in and send off for the prize entry they'd be flexible about it though ;)
Interestingly enough the thesaurus website I use only has the S version and it suggests that if you type in the T version! It only has the T version without the last letter.
The thesaurus site I use
https://www.thesaurus.com/ is not great because it is American spellings :(. It also seems a tad non-PC if you look up synonyms of "Welsh" or "Scotch" ;)
Is there a better thesaurus site anyone would recommend?