Seems you have two separate, yet related issues.
The first, of course, is the language barrier. But it seems that you have the tools in place to deal with this. As long as you always have one of your translators available, you should be all set there.
The main issue is when the PTO meeting turns into something that it isn't. To me, as President of my group's PTO, I look at it as a business of sorts. I always send out an agenda before each meeting, and I follow that agenda during the meeting. Sure there are times when questions arise during the Principal's report, or even during the general meeting, and I will always provide some minimal time, as long as the issue is general, for the Principal to address it. But if I feel that it is starting to take up too much of the meeting I interupt and explain that we can't spend any more time of this, that this is more of a school issue than a PTO issue, and that this would be something that should be addressed offline with the Principal. Some parents incorrectly feel that the PTO meeting is the correct place to discuss school related problems, or even personal issues, but I disagree. It's the time to get PTO related business done...
Your situation is even more difficult as you mention that very often the questions being raised are specifically about their child. Though this makes it even less appropriate to discuss at the PTO (or Parent's Group) meeting, it all comes down to setting the precident.
One thing that I don't understand about your post is that you mention that you are the President, but then mention you were not in attendance at the first meeting of the school year because the school did not inform the parents. Maybe you can explain that a bit more, which might provide some light to your situation. If your school is private, and is overall in charge of your Parent Group, then it's possible that the decision on how to deal with this is not up to you. Is the school private? Are you a non-profit organization? Do you have Bylaws? Are you, as the President, in charge of running the meetings? For most schools that are public the parent group, whether PTO or otherwise, is run by the President and the Executive board. As such, IMO, it is the President's responsibility to write up an agenda, contact the members about the meeting, including the proposed agenda, asking if there is anything to add to the agenda, and then run the meeting.
In the end it all comes down to who is in charge. But if that person is you then I believe that you need to set the precident right away that these personal types of issues are not appropriate for the meeting. It will take some extra time at the beginning, especially with the language barrier, but in the end you'll be able to accomplish your business and your active members will be happier. For now I would recommend that you get a letter out to the parents explaining when the next meeting is, what business you will be discussing, talking about the benefits of getting involved, etc. Have a membership drive if you need to.
Hope this helps,
PresidentJim