Onety

If I could make one improvement in the language, I'd rename the numbers:.

I'd change "ten" to:"onety" and then count like this: 
one, two, three, four, five, six, seven, eight, nine. onety!
Onety-one, onety-two, onety-three, onety-four, onety-five, onety-six, onety-seven, onety-eight, onety-nine, and then twenty. 

Instead of having a language that obscures the number system creating years of unnecessary confusion, we'd have a simple language that teaches the basics of our number system. This would save teachers and students vast amounts of currently-wasted time which could be invested in more useful learning. Or allow for more PE, recess, art, or music!

Confusing Terms

There are words in English that are spelled the same but are pronounced differently and mean different things. It's really confusing. Here's some examples:

Bass - A type of fish.
Bass - A string instrument

Mobile - The city in Alabama
mobile - A synonym of movable or portable

Live - The opposite of dead
Live - A verb meaning where you reside. Example, I live in America.

The Vocabulary site VocabularySpellingCity has a whole useful page about these types of words which are called heteronyms.  I'll quote a bit:

Heteronyms (also known as heterophones) are words that are spelled the same, but have different pronunciations and different meanings. In some cases, the words have similar or related meanings, such as record (verb) and record (noun) – The artist willrecord his new record in the studio this week. In other cases, the words may be completely unrelated, like bow (a knot tied with two loops) and bow (to bend forward at the waist out of respect) – The little girl with the red bow tied in her hair took a bow at the end of the recital. Context clues are crucial to determining which pronunciation (and meaning) is represented by a heteronym.