Translation:He succeeded by having made a lot of effort.
Yes, "...by having made lots of effort." is really awkward English. Some better translations are needed. Why not, "He succeeded having put in a lot of effort."? Note - no plurals in the English as this phrase would include both a single attempt as well as multiple attempts.
Elizabeth. I am just an English learner and your comment has really surprised me. This is the first time I hear that "lots of" and "a lot of" are childish language, I thought they were perfect in any context! Please, could you (or anyone) tell me some different ways of avoiding them? For instance, Would it be better to translate the current sentence as "having made a strong effort.." or something like that? Thank you for any help