Well, it depends on context, doesn't it? Let's have another look at the verse:
ὧν οἱ πατέρες καὶ ἐξ ὧν ὁ Χριστὸς τὸ κατὰ σάρκα, ὁ ὢν ἐπὶ πάντων θεὸς εὐλογητὸς εἰς τοὺς αἰῶνας, ἀμήν.
Let's do a literal translation without any prejudicial punctuation:
"Of whom the fathers and from whom the Christ according to the flesh the one being over all God blessed forever, amen."
Now, that's rather awkward English, so we have to do something with it to capture the sense of the Greek in good English. One way to do that is to render ὁ ὤν as relative clause. Now, you are right -- that makes it sound as though Christ is the antecedent, and to me, the string of nominatives all have the same referent, which is the first nominative, ὁ Χριστός. The rhythm of the text when read straight through also leads me to this conclusion. But what do I know? I only have three accredited degrees in ancient language and literature and 40+ years experience in the language. That's nothing compared to your self study (and RJM's), I'm sure.
I think I alluded to there being ancient and less ancient manuscripts that indicate a separator before ὁ ὢν.
I include more of this evidence.
A BIBLICAL NOTE.
ROMANS ix. 5·
.
.
The fact is that of the four most ancient uncials-Aleph, A, B, C-the latter three ·
have the stop, leaving the following words to be read as a separate
sentence. A is in the British Museum, where it is easily to be seen.
It will be found that the Manuscript has not only a stop, but a small
space to make room for it, both space and stop evidently a
prima
manu. B (Vaticanus) I have twice had the opportunity of inspect-
ing, having obtained access to the Manuscript mainly for the purpose
of looking at this passage. There is a stop, but no space. This has
never been noted, so far as I am aware, in the critical editions, nor
is the point given in the facsimile edition of Vercellone and Cozza.
But the stop is there, nevertheless, exactly the same in appearance as
that found after the word aμfiv at the end of the Verse. Whether it
is from the first hand or not, I do not venture to say. In C (in the
Bibliot/1eque Nationale, at Paris) there is a space w:th the little cross
which frequently stands foe a stop i1t that Manuscript. In the same
library there is another Manuscript, D, of Paul's Epistles (Claro-
montanus), of the sixth century. In this there is a space after σάρκα,
that is to say, the stichometrical line terminates with this word, as
though the writer intended the succeeding words to be separately
taken-in other words, virtually recognizing the stop. Of Aleph
I only know that the facsimile published by Tischendorf has no
stop; but this is scarcely conclusive against its presence, inasmuch
as it may have escaped the editor's notice, as in A and B, of which
Tischendorf expressly, but incorrectly, says that they have no stop.
Assuming, however, that Aleph is without the point, still it remains
true that three, perhaps fom: (D), of the five oldest and most
important uncial Manuscripts contain the stop. I This fact, taken
along with other evidence for the same conclusion, ought, I submit,
to be regarded as settling the question of punctuation. The division
(and rendering) of the Verse given by Professor Jowett in his
"Epistles of St. Paul " is, therefore, correct. And he, I need
searcely add, has here but followed the example of the most eminent
. modern authorities, including Winer, Meyer, Lachmann, Davidson,
Tischendorf, and many more.
.
.
G. VANCE SMITH.
So now you know that there are also a host of famous Greek scholars who see a separator before ὁ ὢν.
But if you read it as two different referents, then you still have to do something with to make that sense clear, so you are stuck with rewording the English no matter which sense you go with.
Winer's grammar 690 (eng trans.)
It is natural that in those sentences particularly which have the character of exclamations,
as in blessings (μακαρισμοί), the predicate should stand at the
head ; in such a case it has become usual to omit the substantive verb.
See Mt. xx i . 9, ευλογημένος ό ερχόμενος εν ονόματι κυρίου· xxiii. 39, L.
i. 4 2 , 68, 2 C. i. 3, 1 C. ii. 11 [?], I P . i. 3 ; Mt. V. 3, μακάριοι ol
πτωχοί τω πνενματι· v. 4-11, xxiv. 46. This remark also applies, as a
rule, to the doxologies of the Ο. Τ. ( Gen. ix. 26, 1 Sam.
xxvi. 25, 2 Sam. xviii. 28, Ps. cvi. (cv.) 48, al. But it is only by
empirical commentators that this arrangement can be regarded as
unalterably fixed; for where the subject expresses the main idea, and
especially where it is antithetical to another subject, the predicate
both may and will stand after it; compare Ps. lxvii. 20 (LXX).
Hence in Rom. ix. 5, if the words ὁ ὢν ἐπὶ πάντων θεὸς εὐλογητὸς εἰς τοὺς αἰῶνας, ἀμήν.
are referred to God, this collocation of the words is perfectly suitable,
and indeed necessary : Harless (see his note on E. i. 3) and many
others are mistaken here,
I also found Jerome's translation interesting:
quorum patres et ex quibus Christus secundum carnem qui est super omnia Deus benedictus in saecula amen...
He uses a relative clause in Latin to render the participial phrase, and his Greek was, I don't know, maybe pretty good?
Jerome, the one who wrote a tract against Helvidius for repudiating the perpetual virginity of Mary.
Helvidius accused Jerome of translating the Vulgate from corrupt Greek manuscripts.
en.wikipedia.org
Helvidius was an exponent of a "conception of Christian morality, which set itself at the same time against the worship of Mary and the saints, and other abuses. This last form of opposition, however, existed mostly in isolated cases, was rather negative than positive in its character, lacked the spirit of wisdom and moderation, and hence almost entirely disappeared in the fifth century, only to be revived long after, in more mature and comprehensive form, when monasticism had fulfilled its mission for the world.
To this class of opponents belong Helvidius, Jovinian, Vigilantius, and Aerius. The first three are known to us through the passionate replies of Jerome, the last through the Panarion of Epiphanius. They figure in Catholic church history among the heretics, while they have received from many Protestant historians a place among the “witnesses of the truth” and the forerunners of the Reformation."
(P. Schaff)
www.ccel.org
Jerome espoused a brand of theology I care nothing for.