Delean is an exemplary race to be sure. I don't know that I'd call it an addon as that typically denotes additions to existing races. (Such as the Raven Master pack.) It is a powerful stand-alone race on par with the old Azurians in terms of effectiveness, creativity, and reliability.
I will be working on Solaron in due course. It isn't a bad race at all, but it is definitely lacking in details. Many of e units are broken in one respect or another, and it has a very unfinished feel to it. I haven't played it extensively in many years, but at a glance it needs a good but of work.
Many of the other races such as you mentioned are merely a motley assortment of units and buildings from other races, OTAK and 3rd party. I don't like them and don't use them. In fact, I will be deleting them entirely.