This is not just semantics. If we look at Luke chapter 6 where the Beatitudes (from verse 20) are preached from a flat place rather than a mount! (verse 17). There are some negative ones as well as positive. The Good News uses How terrible for you.... Other translations especially King James (from where we have got used to Blessed) uses Woe unto you..... If Jesus was really talking about being Blessed the proper opposite would have been Cursed are you that.... He does not say that.
No the Meek and those who mourn are not immediately blessed, they WILL be blessed (in the future) and it is the second part of each Matthew Beatitude which contains the Blessing. The meek will inherit the earth and those who mourn will be comforted.
I am not happy with the Good News Translators use of Happy either, but I see their problem and the beginning of this very sentence (I am not happy with..) indicates that it is possible to use the word happy in the way they have.
Perhaps Fortunate are the meek....... would have been better or even Give thanks you meek for you will inherit the earth..... But then we get a little further from the Greek and English does not provide a neat solution.
There is, in fact, another problem in the Greek, there is no verb. Literally it says Happy the meek, not Happy are the meek. The King James Bible usually indicates this by brackets: (are) or italics: are. This I was taught at Sunday School but it does not seem to be common knowledge. We all need to understand that accurate neat translation is very difficult, if not impossible, especially when we come to think about the Authority of the Bible. Relying on what we have been brought up with is not adequate. And the joke line about the NIV being nearly inerrant (because it suits Evangelical theology) is not at all helpful.