I heard that Hebrew language had no means of determining past, present, or future tense. Could the prophecies in the OT possibly refer to past and future events simultaneously?
You would be right in understanding that the Hebrew verb system is much less sophisticated than the Greek language.
Often times future events are expressed in what is called the “prophetic perfect” tense. In this case future events are spoken of in the past tense in Hebrew. The idea may be that these events are as good as done already. Normally, the context makes it quite clear whether past, present, or future is in view.
There are prophecies which have present and future fulfillments, or more than one fulfillment. These things are not always recognized at first, nor are they solved by the original languages, but by time, as we look back and see how God has fulfilled them. For example, the suffering of our Lord is described in Psalm 22 and 69, but we would not have known this until after the fact.