There was alot more detail than just the 'Holy Spirit'.
Also even the RCC does not state that the books between the testaments are 'inspired'. The Catachism states that they are good for instruction.
Protestants simply recognize the other points of Inspiriation that were recognized by the church to establish the canon.
Just a few of them here.
One; they claim to be holy scripture.
two; other scriputers recognize them as holy scripture.
Three; They do not contradict estabilshed scripture or scriptural teaching.
Four: Their historically accurate.
There are other tests that are valid for scripture that beleivers recognize and make sense. Yes the Holy Spirit brought these simple test out to God fearing men who then stated that these were scripture to the rest of us.
But they are time tested established tests of scripture.
One of the tests that is failed by the books protestants leave out, is direction in morality. The book of Tobit describes a holy angel lying directly. Is this a good representation of morality by a holy one? Is there any other place in scripture were a holy angel lyes?
There are lyes in scripture, almost every time satan speaks. But the scripture simply accurate record what satan said.
Many other things, like are there any verses in the rest of the bible that support the prayer of the living to the dead? Anywhere?
Some people say in Revelations, but just because the elders hear a prayer does not mean it was directed at them.
Again; how long will we be happy sitting in a car with no engine. Then selling that car to others with descriptions of the great trips we took in it.
He doesn't lie, he just doesn't identify himself in a straightforward manner. (That is to say, his "lie" is like you calling yourself "Rhadaghast" is a "lie".)
Hebrews speaks of "those who have entertained angels unaware" (13:2); you can't very easily entertain an angel unaware if they go around announcing that they're the archangel Raphael at every opportunity.