Even Greener Pastures

In Poland we have the spelling contest called 'Dyktando'. It's organised every 2 years and it's for adults. Many politicians and celebrities take part too.
Polish language is rather easy to read when you know the rules but there are a few sounds which can be written different way, e.g. h-ch u-ó ż-rz. These can make a lot of trouble, because their using in writing is based mainly on tradition. Probably they were pronounced differently in the past but they sound equally now. Of course there are rules about them, which are taught at school to young children, but these rules are often unclear and have limited functionality (some of them are useless in fact). For example:
'We write "ó" instead of "u" when in other forms of this word or in similar words in other Slavic languages, exists "o" in this place"
Now imagine a non-Slavic learner of Polish who has to decide...