In those cells, could you check the indicators related to repeated SACCH ? do you see a high amount of calls with RSACCH activated ?
In such cells, AMR calls are more protected and are less prone to interference. In other words, even if RXQUAL is bad, the voice and the SACCH are still holding. So I would consider increasing the HO QUAL thresholds (L_RXQUAL_DL_H_AMR and UL_H_AMR) to 5.5 and the PC thresholds “L_QUAL_*_AMR_RxACCH” to 3.5.
I’m surprised that your SFH PC Thresholds are higher than non-SFH. That should be the opposite.
All my advices are based on the inputs you gave me, which are extremely little. So if that doesn’t work, I can’t be held responsible 🙂