These are questions I've been struggling with lately.
Monday I spent most of the day (thanks to my wonderful mother who watched my son for me so I could) taking ~670 photographs of all of the non-English Magic cards that I own. I got them through various sources - most of them from family who went to Europe and bought a couple packs for me years ago, and a gift subscription a friend (thanks, Derrick!) gave me to The Duelist, the official Magic magazine at the time, which included one pack of every expansion of Magic that came out that year in every language published.
Besides English, Magic is published in Italian, German, French, Spanish, Portuguese, Korean, Chinese and Japanese. The German I had no trouble with - I took German in school, and my wife speaks it with the Boys, so I know enough to identify them easily. French and Italian I know enough to sort out fairly easily. But Spanish vs. Portuguese really gave me a hard time at first - eventually, with the help of the tilde (~) (over n's in Spanish, but a's in Portuguese) and Alta Vista's Babel Fish online translator, I was able to sort them out.
But the Asian languages? Now THEY gave me trouble. I was able to sort them into three piles, basically, after some study. My older son was in Chinese immersion for Kindergarten last year, and actually helped me ID which pile was Chinese. Then my Mom on Monday confirmed for me which one was Korean. Obviously the odd one out is Japanese.
I've spent the last three days using the online Magic search engine I found before to identify the cards' English names, and rarities. Thankfully the Advanced search allows a search by artist, so I was able to, for example, look for any Green cards in Tempest by Brian Snoddy and then just match the picture and I know the card.
WHEW! And, of course, I'm not done yet. I still have to process the photos I took (I wanted to wait until I had identified the cards, since I need to know what to call the .jpg file) and then type up descriptions. I believe some of the photos will end up not being used, as I will most likely end up offering many (most?) of the common cards as lots, which means new photos need to be taken.