A couple of points:
–Are you sure that the leaks are due to electrolysis?
–If the leaks are due to electrolysis, they will be at the union or within an inch or two of it.
–The lack of a dielectric union does not imply plumbing malpractice. An aceptable way to connect iron pipe to copper pipe also includes the use of a yellow brass nipple between the iron pipe and the copper pipe.
If neither the brass nipple nor the dielectric unions are present, that is a code violation and you should bring the connections up to code.