We are well aware of the needed improvements in handling investments. However, please only open a bug if you have found something explicitly wrong. I am slowly working on putting together a list of missing features and needed improvements for investments. This will eventually turn into a blueprint for actually working on those enhancements and fixes. That document will be posted someplace accessible, and an open request will be made for additional contributions and suggestions. Unfortunately, however, this is not likely to happen very soon. Any issues lited here in Discuss, as well as the mailing list, will get included. There are already several bugs in this area, and those will also be included.
I will go ahead and file that bug for the wrong number of digits in shares and prices in the csv export and list the link here later.
I will also read your last post in more detail later, and see if I have any suggestion for easing your short-term pain. As one point, note that since KMM cannot handle cash within an investment account (an original design decision from long ago, that would be too difficult to change without a significant rework of all the investment code) the Investment and Brokerage accounts are separate. CSV export is only done for one account at a time, so you might want to try combining the two exports to see if things look any better.