I do not think SwordSearcher itself has any autocorrect, but Brandon could answer authoritatively.
SwordSearcher does not use autocorrect.
Also, the editor will not change text that you type into it even when it matches text as a verse reference. It will
show the verse reference in the book and commentary panels in the standardized form but when you return to editing, it will be just as you typed it. This is intentional in case of a bad match. The only way around that would be to copy from the panel and then paste into the editor -- that would then use the text the way it appears in the panel rather than what was originally typed.
The only way you would lose what was originally typed is is you deliberately marked the text in the commentary/book panel, copied it, and then pasted that into the editor.
You can adjust what SwordSearcher uses for the "standard abbreviations" in File, Preferences, Bible Book Abbreviations, as
@wsbones pointed out.
Is. is a poor abbreviation for Isaiah because it is such a common English word. By default, SwordSearcher will not match it in the entry editor for this reason. You can control this, though, since Is. is recognizable as Isaiah. Open the editor and go to File, Configure Verse Reference Recognition.
You can exclude certain words from being matched as book names. By default this is the list:
Is is on that list by default so SwordSearcher would not match that as a verse reference unless it was removed from the list.