try increase the following parameters:
DL_ZONE_HO_HYST up to 14dB
UL_ZONE_HO_HYST up to 14dB
HO_MARGIN_INNER_OFFSET up to 10dB
Ping pong shall hopefully disappear 🙂
if you need to increase the amount of traffic in inner zone, try decreasing the RXLEV_DL_Zone (from -70dBm to -75dBm for example), and same for the UL_Zone.