To continue using the often repeated false assertion that Jehovah is
inaccurate because of YHWH using vowel points of ADONAY and that the
Catholic monk made a mistake is just propagating a tradition based on
lack of appropriate research.
From Wikipedia article on Jehovah (bold mine):
According to a Jewish tradition developed during the 3rd to 2nd
centuries BCE, the Tetragrammaton is written but not pronounced. When
read, substitute terms replace the divine name where יְהֹוָה appears in the text. It is widely assumed, as proposed by the 19th-century Hebrew scholar Gesenius, that the vowels of the substitutes of the name—Adonai (Lord) and Elohim (God)—were inserted by the Masoretes to indicate that these substitutes were to be used. When יהוה precedes or follows Adonai, the Masoretes placed the vowel points of Elohim into the Tetragrammaton, producing a different vocalization of the Tetragrammaton יֱהֹוִה, which was read as Elohim. Based on this reasoning, the form יְהֹוָה (Jehovah) has been characterized by some as a "hybrid form",and even "a philological impossibility".
Early modern translators disregarded the practice of reading Adonai (or its equivalents in Greek and Latin, Κύριος and Dominus) in place of the Tetragrammaton and instead combined the four Hebrew letters of the Tetragrammaton with the vowel points that, except in synagogue scrolls, accompanied them, resulting in the form Jehovah.
Development
The most widespread theory is that the Hebrew term יְהֹוָה has the vowel points of אֲדֹנָי (adonai). Using the vowels of adonai, the composite hataf patah ֲ under the guttural alef א becomes a sheva ְ under the yod י, the holam ֹ is placed over the first he ה, and the qamats ָis placed under the vav ו, giving יְהֹוָה (Jehovah). When the two names, יהוה and אדני, occur together, the former is pointed with a hataf segol ֱ under the yod י and a hiriq ִ under the second he ה, giving יֱהֹוִה, to indicate that it is to be read as (elohim) in order to avoid adonai being repeated.
יֱהֹוִה is YHWH.
To get to Jehovah we latinize YHWH to JHVH.
Now we need vowels. These are inserted from adonai. Which was added for superstitious reasons.
Thus Jehovah is a hybrid word. A mixture of the latinized JHVH and the vowels from from adonai.
Of course if God REALLY wanted the whole world to know the correct way to pronounce his name, he could have ensured the whole world did know that one name. A name to run to in a time of distress. But he doesn't. That's why comparing it to Jehoshua, Jehoshaphat, Jehoadah, Jehoaddan, Jehoahaz, Jehoash etc is pointless. They are not the name of God. The name people need to call out to for saving.
Instead people have to choose between a best guess (Yahweh) or a made up name (Jehovah)!
Funny that eh?