Mod 42
That’s an interesting point. My opinion is that since the tefillah is for Eretz Yisrael, once someone starts saying it, it is improper to stop.
I know a Rav who was flying back to the States the night of 7 Heshvan and purposely did not daven maariv until the plane took off. He did not want to start saying tal u’matar and then get into the safek of whether to stop once he got to the States. He felt he could not daven maariv here and NOT say tal u’matar, after all, the gabbai announces it before shmoneh esreh.
It can be confusing.If someone does not want to stop once he started,and goes to chu”l, he says it as a yachid (my opinion), but if he is a shliach tzibbur in chu”l, there is no doubt he must follow the minhag hamakom.