I may have found a fix. After looking at the dump files from the BEX64 crashes, they pointed to access errors in file libcef.dll. I searched around on my pc and found a lot of versions of this file in various locations. Most of them wouldn't work because the hooks Lotro was looking for weren't there. However, I did find one version (libcef.dll 64-bit file version 3.3112.1657.0) that was close enough to the Lotro installed version that it did work, and Lotro would launch. Since I did that last night, I haven't had a launch failure.
Libcef.dll is the Chromium Embedded Framework (CEF) Dynamic Link Library; it seems to be freely available on the internet although I could not find this particular version out there. Here's a Google drive link to the one that worked for me:
https://drive.google.com/file/d/1KDyHruYdW7_3XIF4V2P4L0Ifs1lEGZgF/view?usp=sharingI did notice with Lotro's patch today that the original (non-working) version of libcef.dll was put back. I again replaced it with this one and things worked.
BTW, this is only for the 64-bit client. It should replace only the file under the /x64 folder in the Lotro install directory. Leave the one in the root directory alone.
Of course, it may just be a coincidence...
EDIT: Over a week and it still works okay. However, I have learned that now the store can't be launched in game. If you want to use the store, you need to exit, swap to the old dll, and restart--if you can.