Use ordinary English rather than gobbledygook. It doesn't impress people when you try too hard to use a lot of big words.
Here is an example of a bad sentence in a bad cover letter:
The longwinded sentence...
'Spearheaded the establishment of a new product development department, including the creation of market research, public relations, cross-functional engineering teams and integration of knowledge based systems throughout multiple locations including headquarters, resulting in increasing capacity to be a first mover in the semi-conductor market in Asia.'
Why is it bad? Recruiters have lots of work to do and will not waste time on a letter that takes to long to get to the point. The employer may lose interest and simply toss the whole résumé.
What to do about it? Simple. Read the letter out loud to yourself. If you can't finish a sentence without running out of breath then your sentence is too long and you need to do something like cutting it down or breaking it into several sentences.