I can confirm that Beta 4 seem to have fixed the issue where the transition to SoD was nerfing your XP down to 500,000. That is excellent. However, I am experiencing more (possibly indirect) issues with this component.
Using Tweaks Anthology Beta 4 and SoD v2.1.63.2, attempting to level up a character past a certain level (usually around 3,000,000 XP) results in you getting stuck in the menus. You are unable to dismiss or complete the level up dialog, and so must quit the game. This seems to occur whenever the character would have been given a choice of HLAs, but the HLA files do not exist in BGEE or SoD so the menus hang. Here is what it looks like in SoD v2.1.63.2. Note that the "Done" button is greyed out and can not be selected.
In BGEE v2.2.66.0, you no longer get stuck in the menus when trying to level up, but there are still no HLAs in the game, so you end up with this fugly screen:
However, these modifications to the level up menus do not seem to have made it to SoD v2.2.66.0, so it still hangs on level up.
Even in BGEE v2.2 where you can successfully dismiss the blank HLA menu, transferring your game to BG2EE will not retroactively give you the X number of HLAs you missed in BG1/SoD because of missing files. This isn't good, and it doesn't seem true to the spirit of the Change Experience Point Cap -> Remove completely component. Can Tweaks Anthology do anything about these issues? Including the HLAs from BG2EE should be fairly straightforward, it's modifying the UI that is a bit more complex.