CAT tools - are they really helpful???

Last spring I bought one CAT tool (memoQ) and although I it tried many times already on different files, so far it has proven "helpful" in just ONE case. Everything else has been trouble!
Most probably this is because I am just too stupid, but I suspect some more "basic" reasons too.

For example:
I get a Word file for partial translation = meaning the file contains German, English and Japanese text, of which only the Japanese portions scattered throughout the document need to be translated.
1) I have to import the file.
2) Select all German/English text portions and copy them into the target segement.
3) Translate a few segments, want to take a break or continue working somewhere else.
4) Attempt BACKUP the "project".
=> Get error messages that tell me, I cannot do that. The reasons elude me.
*  In fall of last year someone took remote control of my computer to resolve similar problems with an Excel file, and commented: "Oh, that is a "known issue" = bug. I will try to make the developers fix this."
5) Attempt to "export" the active document, which still contains a few hundred untranslated segments, fails too. Error message:
"At least one of the documents you are trying to export contains errors than prevent memoQ from exporting the document.
Do you wish to resolve these errors now?" Yes ->
6) Results, naturally, a very long list of items/segments, where the "error" is:
"Too few memoQ {tags} in target segment"
This is a matter of course too, since I have yet done anything with those segments!

The customer support tells me:
"It is not possible to simply ignore all the tag errors in memoQ, and export a monolingual document in it's original format, as the missing tags would make that impossible."
7) "Export bilingual" sort of "works" = it gives me a 2-column, intricately interlaced and completely garbled rtf file in which I would have to search and than manually copy each and every already translated segment to the orginal Word file. (Since memoQ cannot handle ODF files, I am also stuck with Word.)

Well, THAT does not make ANY sense. In that case I would be a lot better off using the original file from the beginning and forget about memoQ altogether.
Actually, that was the idea when I tried to "export" the document.

So, with the mentioned ONE SINGLE exception I ALWAYS get the some (or all) of the following problems
* Software cannot import original file
* Software cannot export imported file
* Software cannot "backup" the project
* In order to work on the designated text, I have to work on ALL OTHER text too.* The work put into a file only half finished apparently cannot be recovered be recovered in any sensible/practical way.
* I always MANUALLY have to tell memoQ, that it should ignore various things I would NEVER have to care about working with an ordinary (Word/text) file. There I would for example just a date/number and that's it. In memoQ I am confronted with the need to check "number format", verify numbers, insert tags etc. etc.
What in a word processor is for example TWO keystrokes (for example "10") may well need to required 10 or more "clicks" to get the same thing done!
That is FIVE TIMES MORE work!

This kind of software is supposed to "increase productivity" and make the process of translation easier and more efficient. THAT is not my experience. It makes the translation work more difficult, time-consuming and labor intensive and thus DEFINITELY REDUCES productivity.

Maybe you need very special documents to begin with?
For example during translation of a Japanese patent (in particular the claims) the order in which the individual portions of the sentence are arranged in Japanese differs significantly from for example English or German. So, the "alignment" of segments like "A-A", "B-B", "C-C" etc. does not work. It needs to be "A-C", "B-B", "A-C" or something like that.
I could not yet find out, if the (any) CAT tool would be able to handle that in any labor-easing form ...

But, as I already said, I am probably must too stupid.