Atgames released a new update for the Genesis Flashback HD 2018 last week (v20190226).
The issue with PAL games seems fixed (I've only tested Sonic 2 for Master System and Sonic CD) and the games are running even better in my opinion. The scanline filter is much better than the older version. The core was not changed but they've implemented the improvements from the latest update for the Legends Flashback emulator.
I've made a custom firmware based on this new update in case anyone want to try it.
Features:
-> Genesis Plus GX to load Genesis, Master System, Game Gear and Sega CD games from SD Card OR Picodrive to load Genesis, Master System, Sega CD and 32x
-> Support to mount the games from the SD Card
-> Game Genie support won't work with this update as Atgames changes the emulator and most of the settings for retroplayer.ini are now being read from a read-only file in the /emulator partition
-> The European Firmware is based on the US version but I've replaced the assets, the "About" section will not be displayed as it's the US firmware
-> This update replaces the
data partition. Save states stored in the console will be deleted. Backup them to the SD Card before starting the update
Genesis Flashback HD 2018 - custom firmware based on FB3680_v2.0.1
If the controllers stop responding, you may need to pair them again:
-> Turn off the console and the controller
-> Press A+UP and turn on the controller; The blue light will start blinking
-> Turn on the console, the controller will sync
To mount the rom partition in the SD Card:
-> Create a file mount_sd.ini in the root of the SD Card
-> Copy the backup from your 'rom' partition a 'rom' folder in the root of the SD Card
-> Removing the SD Card and rebooting the device will revert to the original partition
-> Renaming/deleting mount_sd.ini will also revert to the original partition
EDIT: Added firmware with Picodrive replacing Genesis Plus GX