The issue of musical instruments within worship is intrinsically neutral. That is, it is not a matter of faith or morals, so the regulation of their use is completely changeable with the whims of society and culture, but when ratified by the pope.
In other words, the use of instruments falls under the category of a Church discipline, not a doctrine/dogma.
Other issues in this “discipline” category are things like the use of the Latin language, eating meat on Fridays, and the posture used when receiving Holy Communion. If any of the early Church fathers were to dislike these three things, that is nice to know but in no way affects the morality of these things today, as long as we follow what the Church says about them today.
Eating meat on Friday is not intrinsically wrong. But it becomes wrong if the Church says so.
At the other extreme would be something like abortion, which is intrinsically wrong and which can never be changed by the Church.