I would offer. The phenomime of falling back or backward indicted they were under the eternal judgment a sign against themselves just as tongues today is making a noise with no meaning.
The focus would seem to be a Judas used as a new testament type of one who knew not Christ and was eliminated from the twelve apostles which later in respect to the twelve were used as a description of the heavenly City prepared as the bride of Christ ,the believers. the apostles represented the wall that make up the eternal city.
This is just as the tribe of Dan also eliminated from the twelve, with twelve representing the authority of God with tribes, represented gates of the City prepared as a bride. Dan is used in the same way a type. As false prophecy in respect to a serpent so that men fall back to indicate they are under the fiery judgement and not blessing of the lord.
I would not advise and if it is occurring I would pray for rest from it.
Genesis 49:17 Dan shall be a serpent by the way, an adder in the path, that biteth the horse heels, so that his rider shall
fall backward.
How would that have anything to do with the unforgiveable sin if a person does not perform it? Seeing God does the judging. Is doubt a unforgiveable sin ?