The Art of Dying Well, An Ample Declaration of the Christian Doctrine, the Eternal Happiness of the Saints, Steps of Ascension to God, Letter to Foscarini, the Seven Words, On Papal Authority, are all available in etext form in English.

Most should be on the Internet Archive of Google Books (surf with care if visiting, has the normal secular bad content).

http://saintsbooks.net has 'The Art of Dying Well', the others are not yet reviewed and prepared sufficiently to be provided, but should be available in time.

I suspected that 'Disputations on the Controversies of the Christian Faith Against the Heretics of the Age' might not yet have been translated into English, but I do not know this is the case. It sounds like a likely subject for translation.

Yet I cannot find it on the above sources, or Abe Books, which is a used print conglomeration market place that is helpful for verifying such things.

Perhaps someone else knows better.

However this is just the case with the English. If you are looking for the Latin, it should surely be locatable in electronic text form at the above sources.

There are huge amounts of writings of the saints that have not been translated.