Je suis comme le roi d'un pays pluvieux,
Riche, mais impuissant, jeune et pourtant très vieux

I am like the king of a rainy land,
Wealthy but powerless, both young and very old,

I am like the king of a pluvial country,
Rich, but powerless, young yet very old.

That looks certainly better and you too ignore the rhyming part here.

The reason I asked your English opinion is that to me both languages are not my own and the translations looked poorly to me. But I cannot read it in the same understanding you read it.I think it is indeed impossible to stick to the rhyme.
Thanks for your reaction. I like those two lines,ZM. Much closer to the original flavor.

Thanks Olly !