I see to main problems:

How many of you seeing eg. 'zolw' will know that it's 'żółw' without diacritics?

And what about if correct form is with and without diacritics and they mean something different?

I agree that 'Bridges in Athens' should be in English, same 'Churches in Warsow', but some people are trying to mix both English and non-English versions what would give (for me terrific) results eg.

'powiat mikołowski' is name of territorial unit in Poland and correct grammar and orthographic version is as I written, but people are trying to make English version like this:

* 'Poviat mikołowski' - Englicised 'powiat' with Polish adjective (ugly, but correct orthography)
* 'Poviat Mikołowski' - as above but wrong orthography
* 'Poviat Mikołów' - correct grammar and orthograph (Mikołów is noun in  nominative, city name), but something like that doesn't exist
* 'Poviat Mikolow' as above, but without diacritics

As we see all versions aren't really good ;) but first ('powiat mikołowski') is correct in Polish so I think we should keep it ;)

Everything is getting much more bad when we try to apply it to names of churches where are used constructions not existing in non-slavic languages and there is more then 10 different versions and every has some of reveled by me errors.