How to value old MTG cards in foreign languages when none are for sale?
Option 1: Look the cards up on cardmarket.com or other secondary market sites:

Have you tried any other site except for TCGPlayer? There are numerous other sites which let you gain insight on prices of MTG-cards. I'm guessing you live in the US so you may not know about Cardmarket.

Note that this site is mostly used in europe, so prices may differ significantly from the prices in the US. But on the other hand you will find pretty good comparable figures since people often offer cards in foreign languages. Cardmarket also lets you filter by languages and card gradings. 

Other options: CardKingdom.com, magicmadhouse.com, mtgmintcard.com

Option 2: Determine the approximate Value of Cards on your own:

Since the cards you're looking at are pretty old, they are most probably relevant in the formats Vintage or Legacy. Are your cards present in any of the meta decks? If not, they probably won't be worth too much. If they are not in any of the meta decks, how do you evaluate their power level? 


Does it have Strong stats? (if it is a creature)
Combo potential?
Good Value for low mana costs?


If you can answer any of these questions with yes, they may have some value. Certainly this approach can only give you a seperation between potentially valuable cards and bulk. You can never exactly tell the value of a card without having access to the market.