Hello Simba,
There is nothing wrong with the use of uncommon words when you are speaking with someone who can understand them!
To sound more like a native speaker, I suggest changing the word order and a couple of words. In the first sentence, the word, SENTENCES, is a plural noun, so you need to use the word, THEY.)
1. I try to make simple English sentences, but somehow they always end up sounding too wordy.
For the second sentence, you need a comma before and after the word, "however". Using both always AND somehow sounds unnatural. If you want to be verbose, you could add a few more unnecessary words.
2. I attempt to construct concise English sentences, however, and in spite of this, I continually find myself writing in a verbose (long-winded or over-elaborate) style.
Hope this helps