CSV files on mecabricks is a bit outdated and shall be recoded.
Do you know how the csv file shall be formatted for rebrickable? Otherwise, I will go on the website to check that.
If you can wait a couple of days I shall be able to recode the CSV file generator to get an output file supported by them.

The Rebrickable CSV files are setup as follows:

Part,Color,Num (a heading)
x,y,z (x is part number, which is the same in Mecabricks as in Rebrickable, y is the Color ID, but the Mecabricks color ID's are different than the Rebrickable color ID's, but they have a full list HERE --> http://rebrickable.com/colors , z is the quantity of the piece.)

There are no spaces between the numbers and commas. Hope this helps. If not, go HERE --> http://rebrickable.com/help/file_formats

Yep, I had a look yesterday at the file format. I will try something but it might not be perfect. You might have to manually update a couple of parts in the file (I'm thinking about decorated parts as my references are different from them).

I'm also reworking the material library for the moment to add more colours/materials and improve the rendering quality in the workshop. Anyway, I will add the corresponding rebrickable colour ids so that it will be correct in the csv file.

I'm currently working on the material library. I'm planning on adding legacy colours as well as materials like rubber, chrome etc. For now, I'm summarizing all the information I find in a table to decide what is relevant or not. In the same time, I'm recording the colours IDs for multiple systems - LEGO, bricklink, LDraw (rebrickable is similar) so I will be able to generate the list you want.