The organiser of Hong Kong’s flagship arts event was almost a year late in filing tax returns for nearly 30 overseas artists who performed at the 2018 festival, the city’s chief auditor has found.The Director of Audit’s report on Wednesday said it was a “matter of priority” for the leaders of the Hong Kong Arts Festival (HKAF) to submit tax documents to the authorities for 29 performance contracts for last year’s month-long festival.The city auditor also urged the non-profit HKAF Society…