"but wasted little time in making up the ground he had lost by debuting so late."
First, the "debuting so late" is redundant (you've already used it so we know what we're talking about without repeating it) and for that matter, I don't know if it's even "legal" to make a present participle out of a foreign word by simply adding an English -ing to it. I know it certainly is a difficult word to read - we want to pronounce the T in it, and we shouldn't. So, for that reason alone, I would get away from using the word in writing.
That leaves us with "but wasted little time in making up the ground he had lost." This is fine, technically. But as you asked for a more comfortable rephrasing, I might suggest "but wasted no time in making up for lost ground."
And yes, "wasted little time" and "wasted no time" mean the same thing, more or less. It's a matter of emphatic degree. "Little time" suggests he did waste "a little," while "no time" is clearer - he wasted nothing. But both are idioms that really shouldn't be taken absolutely literally.
It is amusing to note that if you put an article in that expression it completely reverses the meaning. "He wasted little time" means he jumped right to it, fast. "He wasted a little time" means he held back, waited, and, indeed, wasted time!
Crazy language eh?
Student or Learner