I don't think I agree with your 55% for spelling. Most of the books and experts I studied when training ( not in primary ed but as a specialist) gave much higher figures than 55%.
Because I had seen many different claims about how regular or irregular English spelling is, I decided to establish this beyond a shadow of doubt by analysing the spellings of the 7,000 most used English words. I found that 3,695 of them contain one or more unpredictable spellings (frIend, cheQUered, coPy - cf. poppy).
The people who claim that English spelling is more regular than it is are nearly all apologists for English spelling. They try to make u believe that it is not nearly as bad as it is, and that bad spelling is simply the result of bad teaching.
Re
wag - was, ear - early, dream - dreamt, now - slow.
Unlike any other alphabetically written language, English poses spelling AND READING difficulties. - The others have no spellings with more than one pronunciation like the above.
'Wag' makes regular use of those letters, but because 'wa' is an almost regular subpattern for the /o/ sound (was, want, wash), this creates reading difficulties.
The /ee/ sound has a completely unpredictable spelling:
eat ? eel, even, ceiling, field, police, people, me, key, ski, debris, quay (ea in 152 words ? other spellings in 304),
and because [ea] has several sounds (treat, ear - great, threat, wear) it poses decoding difficulties as well (unlike ee which has just one sound, like all spellings in other European languages do.)
A final -o (go) has several unpredictable spellings (toe, snow, though, sew), and as u pointed out, ow has two pronunciations which children have learn to read correctly in different words.
For reading, context helps them with choosing the right one.
For spelling, they simply have to memorise the correct spelling for each word.
Masha Bell