First, systemic (and economic) are adjectives. There are a number of similar words with different meanings. Systemic and systematic are adjectives with different meanings. ‘Systemic’ means that it is inherent to the system, that it is related to how the system was created. There’s systemic corruption in the licensing procedure. (It’s widespread and results from the system in place) ‘Systematic’ refers to being thorough and complete. After each airplane crash, there is a systematic review to determine the cause. (There is a defined procedure to examine every factor) ‘Systematical’ is usually used to mean ‘systematic’ but it’s neither as clear a word nor as accepted as ‘systematic’.

With the -ic ending as in economic, mechanic, systemic, you are using the noun form. Systemical, economical, mechanical are all adjectives.