FM to MIF

You should never use MIF 7 for any FrameMaker version 8 or higher. Version 8 introduced Unicode.

Therefore you should use MIF 2019.

After translation you might get some alerts, when opening the files in FM 12, but you can ignore them, as your source was already FM 12.

I can't answer the translation question.

There is no way to save all the files in a book to a different format without using a plugin of some sort, either a DLL or an ExtendScript. That being said, Adobe still provides the BookMIFWash.dll as an "example" utility, which will do most of what you want since it does not delete the MIF files after performing the wash. Note, however, that it saves ONLY to the most recent MIF format.

1.     Close FrameMaker

2.     Copy BookCompmonentMIFWash.dll from:

               C:\Program Files\Adobe\Adobe FrameMaker 2019\Samples\ScriptsAndUtilities\BookMIFWash

          To:

               C:\Program Files\Adobe\Adobe FrameMaker 2019\fminit

3.     Add the following to the [APIClients] section in your maker.ini file in the fminit directory:

              MIFwash=Standard, MIF Wash, fminit\BookComponentMIFWash.dll, all

               (NB: you need to use your text editor in administrator mode, or Windows will refuse to allow you to edit or update.)

4.     Restart FrameMaker and use the Book Utilities menu in the menu bar to save your files out to MIF format.