English translation

This is a very good translation, but there are a couple of small errors in it:

"ainsi" doesn't mean the same thing as "même", not at all.
"chante ainsi le gardien de phare" is translated as if instead of "ainsi" it was "même";
so rather than "even the lighthouse keeper sings" it should be "the lighthouse keeper sings like this". This error is repeated in the next stanza, "even the seminarian sings" should be "the seminarian sings like this".
Or "thus" could be used instead of "like this".
Also in the "seminarian" stanza, the usual English word for an agenouilloir in a church is "hassock"; (I think probably Brassens was making an irreligious pun when he said "reposoir" which, in a church, is the whatever the host is placed upon after being consecrated, but anywhere else is a place to rest or a thing to rest on - but I can't see any way of reflecting that pun in English, and anyway he may have used reposoir simply because it fits the netre and agenouilloir doesn't). Your "kneeler" isn't wrong but it's rarely used in that sense.
In the penultimate stanza, first line venu definitely means "come" but it wouldn't be unreasonable to translate is as "gone"; But it can't be translated as "been" here because that would imply that he had left the Arc de Triomphe before the time referred to by the verb in the main clause (entendis), but "Á l''Etoile" clearly qualifies that verb so he can't have left before that time. (When it's OK to use "been" as a past participle of "go" isn't easy to work out - in this context it would be interpreted as the past participle of "be", not of "go").
in the final staza, you've pick the wrong sense of "mettre un point final"; "put a final stop" means something like "destroy it" or "bring it to an end" (which are probably the most common meanings of the French phrase although they don't make sense in context). What you need here is something like "add a final touch".

The last line beginning "to" after "to the lonesome" sounds a bit odd, a more natural English would replace that second "to" with "that they". ("they" plural because there's a transcription error in the previous line, it is actually "aux solitaires" not "au solitaire")