One fragment of 2 Chronicles is practically nothing, and it isn’t even certain the fragment is from Chronicles rather than a related text.

Agreed on both counts; the identification of 4Q118 has been questioned, and the safest wording is probable rather than certain. This is a thin data point. The near-absence of Chronicles at Qumran is more likely a fact about the community’s interests than about the book’s existence, since Chronicles is quoted and known elsewhere in the period. It is listed here for completeness, not as support.