At my end, I wanted to import [the Wordfast] memory into my TRADOS memory but that just does not work.
Open the Wordfast memory in Excel (set all cells to "text" first, else Excel might try to calculate cells that start with a number). Grab the source column and target column, paste them into two text files, and do an alignment in Trados. If the Trados aligner is any good (don't know if it is), this operation should be painless.
Minor quirks may occur.