Showing some partial content in a way that works well across multiple languages is a hard thing to do. Depending on how you want to deal with it, you may need to take into account how each language separate words, use a different line according to their script, or the very notion of "character" and how those are counted.
It would be useful to have a generic component in MediaWiki that let's you just show a given number of lines, or whichever content fits in a given space. This is something that the Language Team may consider to support in the future.
An alternative to cropping with an ellipsis, could be to make the last part of the text to fade out by applying a transparent-to-white gradient on top of it (covering the last line).
Regarding the continuity problem mentioned by Connor, that can be solved if when reaching the article though a hovercard, the first sentence of the article gets highlighted for a second (e.g., background could fade to grey and back to white again). In that way, the user could guess that the text is the same and continue reading where he/she left.