We need a closer look at the verses preceding Proverbs 4:18, which reads as follows in the Jehovah’s Witnesses’ New World Translation: “But the path of the righteous ones is like the bright light that is getting lighter and lighter until the day is firmly established.”
An examination of the context shows that the passage is contrasting righteous people with wicked people. The “path” in this context refers to their respective lifestyles, not to the development of doctrine, as the Watch Tower Society (WTS) would have us believe.
The “bright light” represents the righteous person becoming increasingly obedient to God’s commands and living a virtuous life. There is no warrant whatsoever for claiming this passage deals with an increased understanding of Bible prophecies.
What the WTS calls “refinements” or “adjustments” are in actuality instances of it having made false predictions or having taught false interpretations of Bible passages. When these blunders come to light (no pun intended), the WTS scrambles to disguise them, alleging that its understanding was not fully developed and thus needed an “increase of light.” In other words, when the WTS changes a doctrine (by reversal, flip-flop, or outright elimination) or when it wants to slough off a false prophecy, it asserts that “new light” has been received and has enabled it to better “understand” a teaching or prophecy.
The former teaching (“old light”) is then discarded, and the “new light,” which is called a “refinement,” supposedly brings the WTS to a fuller understanding of the prophecy or teaching in question. But truth neither changes nor contradicts itself. If a former teaching were true in the first place, there would have been no need for any changes. Truth does not grow “truer,” and its essence does not change to something else. In the case of the WTS, we do see current teachings contradicting earlier teachings and doctrines going back and forth between opposite interpretations. This is not maturation but mutation.
The Catholic Church has never changed any defined doctrine. Disciplinary matters, such as priestly celibacy or abstaining from meat on Fridays in Lent, can and do change, but these items are not doctrines and do not come from the deposit of faith left by the apostles. Consequently, the Church may change or dispense such matters as it sees fit.
Also, while you may see certain differences and even changes within or between the teachings of individual theologians, but when the Church defines something as dogma, it doesn’t change.
For developments in Catholic teaching to be grounds for accusations of false religion, these would have to involve reversals of defined doctrine. But this simply has never happened in the Church’s entire history.