The word "in-successes" does not exist in the English language. However, we can provide synonyms for two possible interpretations of this term.
If "in-successes" is meant to describe a lack of success, then some synonyms could be failure, defeat, setback, disappointment, or frustration. These words all convey a sense of falling short of a goal or expectation.
If "in-successes" is meant to describe successes that are not widely recognized or appreciated, then some synonyms could be hidden triumphs, unheralded achievements, or unsung victories. These words all suggest that the accomplishments in question are significant but have not received the attention or recognition they deserve.