1. Loaded DirectX for Modern Games in the correct bottle:
https://imgbox.com/3P8iNKEl
2. Started game.
3.Usual error message popped up after a minute or so.
4. Stayed ingame for another five minutes in High graphics mode, including some test combat; no apparent problems.
5. Reset graphics to DirectX 11 via in-game Options.
6. Restarted Mac.
7. Launched Crossover.
8. Reached final loading screen, "Enter Middle Earth".
9. As soon as the loading bar at the bottom of the screen was full, game crashed to desktop.
10. Relaunched LOTRO.
11. At character selection screen, Options, reverted to DirectX 9. Quit game.
11. Relaunched LOTRO.
12. Except for the usual error message, working fine.
13. Reset from FullScreenWindowed to Windowed via ingame Options, no apparent ill effects (I like to be able to run other programs, like Discord, from the dock).