Well, without Hawk-Eye, you've no choice but to trust the linejudges to be impartial and professional.
He played U-15 national semifinals and U-17 Finals. He had to play doubles also (nearly 10 matches for 2 days). So, he conceded U-15 semifinals to Lakshya sen due to fluid loss and he went to hospital to inject intravenal fluid and came back home past midnight and took LS in the morning for U-17 finals and won him in 2 straight games.
Lin Guipu is knocked out by Lu Chia Hung, he has only himself to blame, so error-prone, and LCH was defending better and making far fewer mistakes.