They are ZLIB compressed with SARC files inside. At least for the one file I tested in a Lyt folder. Not sure if they are all SARC inside the ZLIB files, but the fzip files are ZLIB files with a different header on them. I would share an extracted file, but it would be illegal to share.
Byte 0x00 - 0x04: is the FZIP Header
Byte 0x05 - 0x08: is the size of the decompressed file
Byte 0x08 - end of file: is the actual ZLIB compressed file
Edit 1: The file in the common/msg folder is a WARC file which looks like a SARC file when decompressed, but the contents can easily be read. Starting at offset 0x1A6B4, it looks like that might be the word list in Unicode format.
Even if that isn't a word list for that game, there are some other TXT2 files inside the WARC file that have random words in them too. One of them has to be the word list used.
If anyone needs more specific info, I'll be glad to help. I wish I had the motivation to create an editor for the game, it would be simple to do, but at this moment, I'm just not up to it. Sorry.
Edit 2: After some further research though, I discovered that the WARC file actually contained MSBT files in it, and there are some tools available to edit those. So if the WARC file header can be decoded to easily edit, then the MSBT files within it can easily be edited. Right now, you can easily copy/paste the MSBT section out, save as a MSBT file, open in a MSBT editor, change the words, save the file, copy/paste the code from that back into the WARC file, making sure the file size is smaller, since the header isn't quite figured out yet. Then you can recompress the file with zlib, add the header back on, and then replace the game file with it. This is fairly easy and basic modding, and hopefully I've given enough info for anyone that feels like making an editor, so they can make one, hopefully a well designed one with a GUI, and not some command line hack ...
Here is a MSBT file I extracted with a hex editor opened up in the MSBT Editor Reloaded which can be found here -
https://github.com/IcySon55/3DLandMSBTeditor/releases/tag/v0.9.1
The release thread for it is here -
https://gbatemp.net/threads/release-msbt-editor-reloaded.406208/
