Apparently the Gazelle's were pretty accurate. The MiG-29 and Orao attack jets not so and mainly missed their targets with unguided rockets and dumb bombs.
The article questions why Serbia is still using Gazelles in AT role when they have new Mi-35s. Only 4 Mi-35s have been acquired so the Gazelle continues in the AT role as well as training, light utility and observation.
Serbia's recent aircraft acquisitions:
6 MiG-29 donated from Russia. These are being upgraded and bring fleet to 10 MiG-29s. Belarus donated another 4 but these have yet to arrive and given Serbia slammed Lukashenko, they may not arrive.
5 x Mi-17V-5
4 x Mi-35
9 x Eurocoper H-145 (4 went to police, 5 to air force)
6 x CH92 UCAV (Chinese) + 18 FT-8C Laser guided missiles
Air defence saw following orders:
6 x Pazars SHORADS
50 x French Mistral SAM. Yet to be delivered. Some of these will equip Pazars
6 x Pantsir S1 (now there's wasting money given its poor performance).
There was a plan to acquire Chinese FK-3 long range SAMs (roughly similar to Russian S300) BUT given in the Washington Agreement the Serbs signed some anti-Chinese provisions I don't know if they will get it.