I introduced some my friends to Slovio and Slovianski, and they had problems to analyse and find out that broda, brada and boroda are the same word! I tried to tell something about Proto-Slavic *tort/*tolt, but they become fed up with linguistics soon. If there is any rule set, for example, Russian -oro- becomes -ro-, my friends who are not interested in linguistics at least can learn it (as do those who are learning Polish (broda) or Czech or Serbian (brada)), and so can I use this rule - I don't want to look to the dictionary everytime I want to write a word!
It gets worse for non-Slavs! How can they guess that korol and kral is the same word? How can you imagine if one user prefers "kral" and other "korol" - how will an American, a German who doesn't know any Slavic language recognize the word he has learned from Slovio dictionary?
And in the end nothing will prevail, I'm sure, because following your idea, Serb will keep on writing "zlato", "brada" and Russian "zoloto", "boroda" and they will never find a compromise!
And words like "rodzin" will ALWAYS be misspelled by majority of Slavic users and they will confuse non-Slavs (and some Slavs also), who don't know that in Polish language "dzi" is etymologically equivalent to "di"! Sorry that I repeat myself, but some men here still seem to be dug up and don't realise the things.