Sorry for the late reply to this conversation, but I just noticed the forum hasn't been telling me about all topics, and I feel there is information to add on this one.
First off, the reason you couldn't decrypt with real versions of TrueCrypt (and had to use the decrypt-only version) is because TrueCrypt only supports in-place encryption and decryption of system drives. It warned you of this when you encrypted the data drives 3 years ago before you placed any data on them.
Second, the data drive you completely lost sounds like it had a physical failure. Unfortunately, when a drive physically fails at sector 0, it is pretty difficult to recover from. It is also a bad sign for other sectors, so writing any more data to it is a bad plan. I would guess that trying to decrypt the drive did indeed corrupt it, but due to hardware problems, not TrueCrypt problems. If it was due to TrueCrypt problems, the fact of the matter is that you forgot what TrueCrypt told you it did and didn't support and decided to trust a version that is believed to have been released as a warrant canary and counter to everything TrueCrypt stands for, so I wouldn't be too concerned about older versions causing this problem in the future since they don't support what you did to begin with. FYI, Your best course of action probably would have been to use a Linux tool like ddrescue to copy the entire readable raw content of the drive to a new drive ASAP. Then you could have possibly used the rescue header to mount the drive. If it still wasn't possible to view data on the drive due to corruption, you could have used a file recovery tool against the mounted and decrypted but corrupted volume.
Third, any time I install an OS, I physically disconnect all drives that I don't want the OS to touch. That would have prevented you from having a drive overwritten with Windows 10 install files. I actually take it a step further and don't use dual boot functionality. I set up each OS with its own boot drive and use the BIOS to determine which OS to boot. This isn't as simple, but it avoids compatibility nightmares like yours. Unfortunately, this might be less and less feasible as it seems like there are more and more bugs in the BIOS these days and with UEFI we may eventually lose some level of control on any machine that isn't custom built.
EDITS: removed some adjectives not necessarily friendly to non-native English speakers (and/or non-English translations) and fixed a spelling error