How many keywords am I allowed to use according to each language?
It depends on each market / language requirements.
It is much more complicated than just how many keywords are recommended: Some languages allow a certain amount of keywords but they must not exceed so many characters ... other markets allow different amount of keyword combinations according to their total added length (a keyword combination may be made up of 2 to 4 words i.e. "French search engines" or "search engines in French").
The rules are completely different with Asian speaking search engines since it only becomes a matter of character allowance ...
In other terms, it is different for each market and regularly evolves according to the ever-changing ranking criteria updates from major search engines and directories. We will guarantee that your multilingual pages will always respect the ongoing rules and regulations from major search engines and directories as long as we are in charge of submitting them .