For more times than I can remember, I have heard shlichai tzibuur render a brocha in Shemoneh Esrai incorrectly. It is Go-ail Yisroel, the redeemer of Israel, not ga-ol Yisroel, which is the bracha before Shemoneh Esrai. I have heard this error numerous times, even from people who have gone through the yeshiva system and are no longer young.
Perhaps these kinds of mistakes are made by people who habitually talk during davening and never got their davening straightened out.
I don’t know if you can make that conclusion. Seems more a problem that started when they first learned keriah and davening and no one ever corrected them.
To be honest I don’t recall ever hearing that mistake.
What really bugs me is when the shat”z whispers the beginning of Modim to himself. He’s supposed to do the exact opposite, to say it loudly enough that everyone can hear it over their own Modim D’Rabbanan.
Yes, that Modim issue is another pet peeve. How closely are you paying attention to chazoras ha-shatz?
In my school minyan in South Africa I remember that the chazan siddur had the tzeire under the alef of Go’eil Yisroel circled. But not as you would imagine, each dot of the tzeire was circled and then it was underlined, so you couldn’t miss it.
The problem was when it started to look like a weird smiling face and disturbed my concentration, but still I’ve never made that mistake.