Hmmm...I'm sure your reply was different when I quickly glanced at it yesterday
I've pretty much only used Linux systems for the last 15 or so years, but do have Windows 7 I run in a QEMU Virtual Machine that I use for updating my Garmin devices when required.
JaVaWa TYPchanger did the job nicely using that.
I removed the MicroSD from the 700, put it in a reader ensuring it was accessible in the VM, then drag/dropped the map and typ file into TYPchanger, within about 10 seconds it was successfully finished.
As for editing the typ file that came with the topo map, that's a whole other story...
Experimented with a typ file I had here and found it wasn't to my liking in the topo map, so thought while I was using Win7 in a VM I might as well use TYPviewer to make some changes to the original that came with the map.
Turned out TYPviewer wouldn't even open it in the Win7 VM, it kept crashing out with an error about something or other.
So I downloaded Typwiz7 and it seemed to open it ok, made a few changes then discovered a license was needed for it to save the full typ file correctly.
Decided to use it and TYPviewer side by side, going through everything in Typwiz7 and creating a new typ file in TYPviewer creating the same display elements one at a time from scratch.
That sort of worked but I hit a snag after a while when I discovered a lot of the polythings shown from the original typ in Typwiz7 were "Customizable_Line_9" etc. and it was practically impossible to figure out what the hell Garmin had used each of them for, and there's only 1024 of those to choose from for each newly created one
So I've now spent most of last night and today creating and testing a typ from scratch again in TYPviewer and just included everything I reckon it would need to display all the map elements correctly, which it does except for one thing, fences, it shows the labels ok but the fences themselves aren't visible as they're the same colour as the land area, white during the day and black at night.
I cannot figure out what polylines are used for them and everything I change to try and get them to display correctly on the map so far hasn't worked, they remain invisible except for their labels.
Seems I just stumbled across something that might help me sort it out, I just loaded the original typ file from the map into TYPviewer on my Linux system (runs under WINE as a lot of Windows software does) and it didn't crash like it did on Windows 7 and loaded the typ properly, wish I'd thought of trying that last night...