Trust your feelings. First of all, the author got two independent clauses connected by however. Using the commas misleads the reader into thinking the word is just an adverbial aside. Use a semicolon to emphasize that it's a conjunction:
Cloning must be researched and funded; however, ....
The author has written himself into a corner. He can't leave out the comma after battles, since it will mislead the author into parsing another object of the preposition of, but retaining the comma will mislead the reader into expecting another independent clause. I think the best you can do short of a complete rewrite is add the missing to from promote to emphasize that there's a modifier of compound infinitives
... its human involvement must be limited to prevent a veritable onslaught of ethical and legal battles and to promote its potential
health and societal benefits.