Are these Messianic Jewish baptisms valid?
Some Messianic Jewish congregations baptize "in the name of the Father and of the Son and of the Ruach ha-Kodesh." Are these baptisms valid?
They probably are. Ruach ha-Kodesh is simply the Hebrew phrase for "the Holy Spirit" (Ruach = Spirit, ha-Kodesh = the Holy).
We already know that there is some flexibility in the translations of the terms used to refer to the Persons of the Trinity. For example, in English the Holy Spirit is often referred to as "the Holy Ghost" (especially in older works or in Traditional circles). It is valid to baptize using the term "Ghost" instead of "Spirit."
In Messianic Jewish congregations, a special sub-dialect of English is used in which Yiddish and Hebrew loan words are used as part of English speech. Thus if you were to attend a Messianic Jewish service, you probably would hear a sermon in English on Yeshua ha-Mashiach, which is Hebrew for "Jesus Christ."
As part of the daily speech they have been taught to use in church, many Messianic Jews naturally use Yeshua ha-Mashiach to refer to Jesus Christ and Ruach ha-Kodesh to refer to the Holy Spirit. It is part of their sub-dialect, just as "Holy Ghost" is part of a more traditional sub-dialect of ecclesiastical English and "Holy Spirit" is the mainstream usage within ecclesiastical English.
One can argue that Ruach ha-Kodesh is simply a term in an English sub-dialect, just as "Holy Ghost" is. English is a composite language made up of loan words from other languages in the first place. In fact, "Ghost" is from Old High German, while "Spirit" is a loan word from Latin, and "baptize" is itself a loan word from Greek.
Thus these baptisms are probably valid, even though, in the case of a Messianic Jew who becomes Catholic, a conditional baptism might be in order, just to make sure.