I call it "Beis Tefilla English". The local RBS Torah publication is riddled with it. What's with the Hebrew-within-English? Why not transliterate like... in the rest of it?
I can't help imagining that he started writing that way and then realised that if he would carry on like that it would come out like this:
With immense gratitude to הקב"ה we are delighted to inform the ציבור regarding the ברית of our son which will take place אי"ה at the hall in בית תפילה יונה אברהם, נחל רפאים 34 on Friday morning at 8:00am. May we continue to share שמחות!
So he decided (I imagine) not to keep writing in Hebrew because it looks silly and is hard to read. But in that case - why not fix what you already did???
Personally I really dislike the Hebrew-words-in-Hebrew style, but if you're going to do it, go all the way. If you can transliterate some times why not every time? Most of us will find it easier to read that way. Only write in Hebrew if you're quoting something where the spelling is important etc.