Rebuilt disk will be corrupt, but if the disks are really failing there will always be some data loss, you can also use ddrescue on all the failing disks, this way at least you can know which files are corrupt.
Sep 14 01:00:01 tower1 kernel: shfs[25263]: segfault at 0 ip 00000000004043b8 sp 0000146026a3d780 error 4 in shfs[402000+b000]
shfs segfaulted, rebooting should bring your shares back, but if it continues to happen it might indicate an underlying issue.
First we need to know if this was a one time thing or if you keep getting sync errors after they were fixed, so if that was a correcting check run another one, also you're overclocking your RAM and that is known to corrupt data with some Ryzen servers, see here for max officially supported speed for your config.
Sorry, missed your first reply due to an old forum bug, filesystem is crashing immediately after mounting, there are some recovery options here that you can try.
I forgot the device is USB, so not so easy to check if a driver is being loaded as if it was PCI, but that's likely the problem, you can make a feature request for the driver, LT are usually good at adding them quickly, if one is available.
During the rebuild of disk1 there were read errors on disk5, do disk1 can't be correctly rebuilt, check/replace cables on disk5 and post new diags after array start.
Posted diags don't show what happened to disk6 so can't comment on that.
They can cause sync and other issues like dropped disks and are not recommended, but they do work for some, so if you already have it might as well see how it goes.