If there is one thing I would change, it would be the alphabet we use. 1 letter for every sound. “A” has so many versions, e.g.
Only problem is we would probably end up with 75 letters.
My personal favorite is the fact that when a house burns down it also burns up.
And flammable and inflammable mean the same thing.
The letter "a" can have at least six distinct sounds, as represented by the words Able, Apple, All, Arrow, About, Any. These sounds can vary according to accent and dialect. For example, I pronounce Mary, Marry and Merry exactly the same, but there are those who pronounce each of these words differently.
I have read (but have no personal experience with) that Finnish, along with Hungarian, is an extremely difficult language with several (like more than a dozen) declensions of nouns and adjectives that English is mercifully free of (except for our pronouns which come from Norse). So Finish may enjoy rational spelling (like Spanish) but the rest of its grammar is incredibly complex.
English is a difficult language for non-native speakers to master, but oddly a very easy language to get by in. “No tickee, no shirtee” is often cited as an example.
Ah, but spelling. GHOTI
Of course it is pronounced “fish”
The gh of tough, the o of women, and the ti of nation.
If you think that English is bad try learning the 2000-3000 characters you need for Chinese. Of course you could also try to learn all 85,000.
English also has a marvelous and unique proclivity for making nouns into verbs, almost without limit. We can "Google" something or "railroad" someone. One of my favorite examples was in the film, "The King's Speech", when King Edward's brother asks him what he has been doing lately, he replies the he has been "kinging".
I remember reading an essay many, many years ago that maintained that literacy problems were higher in English-speaking nations and blamed the problem on the irregular spelling issues. The problem, the writer stated, stems from the fact that English adopts words with their foreign spellings intact rather than spelling the new words in a way that conforms to English pronunciations.
For me, the strange spellings make English more interesting. But, admittedly, I was born with a brain for spelling. I can see how the many variations are confusing to those whose brains work differently. (My mental challenges are great, but they are related to spatial and numerical configurations.)