Agreed about the need to use full rhyme in couplets like the original. Yet, the lines in English could be written in ten syllables. Twelve would be stretching things in English. As for the caesura after the sixth syllable, I'm not sure what purpose that would serve nor if it would be desirable. In any case the caesura is not always present after the sixth syllable in the original. Let the breathing pause in English fall where it may. English pentameter is a homologue to the French alexandrine. Traditional IP can do the job.
Added in:
I spent some more time with the French as promised. Before you begin your rewrite, here are a few pointers.
The French:
On voit, sur une route au pays de Pontcroix,
En plein ciel, toute neuve, une pompeuse croix
Où resplendit un Christ badigeonné de rose.
Your translation:
Along the road in the region of Pontcroix
A brand new cross looms large against a full sky
With a gleaming rose-washed Christ, commanding awe.
The French has “pompeuse,” which shows this crucifix to be bombastic, pompous. That is also what your crib and the second crib state. I take Breton to mean affected, precious, not “commanding awe.” My justification is that later in the poem Breton describes the virtues of the other cross and its humble and humiliated condition. It is the virtue of the peasant who made a simple cross of stone versus the arrogance of a gilt cross made by an unmentioned hand, distant, abstract, theoretical, maybe even theological. In keeping with the original you need to drive home the dichotomy of the two crosses. For the record, I find Breton's
Pontcroix or "Crossbridge" a bit over the top. The bridge is between two crosses that are far apart? Not so convinced.
Et l’éternel Souffrant, qui calme la douleur,
Rappelle, en cet état, les âpres agonies
De tant de nobles coeurs jetés aux gémonies
The Eternal Sufferer who calms all pain,
A Christ whose sad and sorry state recalls
His own and others' bitter agonies,
Those noble hearts cast into obloquy,
Forgotten like this Christ who suffers shame.
I don’t follow your English from the French here. There’s no reason to have five lines of English to three in French. It’s sometimes the other way around! Where did you get “shame”? You take up a lot of syllables for the equivalent of
en cet état:
whose sad and sorry state. In fact, the French doesn’t say that and is far simpler and direct.
It’s not “his own and others’ bitter agonies” (prefer “misery”), but that the Eternal Sufferer (long-suffering) brings to mind the bitter misery of so many noble hearts subjected to public scorn.
Nowhere does the French say “Forgotten like this Christ who suffers shame,” which has to be the worst line in the translation. And we've all written them!
Here’s one more to encourage a closer look at the French. In your crib, the final lines end with two questions while your verse translation ends with a declarative sentence. The original goes:
…croyais-tu que l’oubli
Oserait te jeter dans un trou de muraille,
Et qu’outrage dernier, l’insultante broussaille
Mêlerait sur ton front, qui saigne et qui bénit,
L’épine de la ronce à celle du granit?
Your crib:
…thought thou that
oblivion/neglect would dare throw you into a hole in the wall?
And the final/last insult/outrage, the insulting brush/scrub
mingled (should read: “would mingle” like “would dare” after main verb “thought”) on your brow that bleeds and that blesses,
the prickle of the bramble in that of the granite?
Your translation:
yet now/
You’re lost inside a cleft. O magnitude!
The final insult on your blessed brow,
A brow that blesses and a brow that bleeds,
Are prickly brambles that have become your crown,
And the rough-hewn granite wall among the weeds;
That seeks to banish you into oblivion.
The translation is very distorted here. Where did you get “you’re lost inside a cleft”? Is this a rewrite of the French (jeter dans un trou de muraille)? How does “magnitude” come in? Nowhere do we get the question “Did you think that oblivion …?" But it is oblivion that is the agent of action in the French. You make it into the object of a preposition and at the end of the poem!
The "insult" is not "on the brow" but the "insulting brambles" "would mingle" the nettle and granite upon his brow (between a weed and a hard place). Your translation unnecessary conflates "outrage denier" and "insultante," then goes onto "brambles" unrelated to "insultante" as it is in the original. Instead "brambles" is connected to "prickly," which becomes a pleonasm.
Why "banished"?
In all, you miss the unworldly grandeur of the provocative question
did you believe that oblivion would dare to throw you into a hole in a wall and that, final outrage, the contemptuous undergrowth would mingle upon your brow, which bleeds and blesses, the needle of the nettle with that of the granite. Your rendering of these lines is quite a Gordian Knot. I think you forgot the French for the English.
This stone Christ is cast out yet shall be the corner stone of the new Temple. Perhaps Breton despairs that no such temple will be built or that the true Christ is always meant to be among the downtrodden, outside the Temple walls, among those who suffer. On the other hand, if the Temple is built Breton might be suggesting it would be like the golden cross of an established church. Is he being spiritual or political? The poem holds interest in this way.