You don't need a registered agent in California, but you do in Delaware. Usually, the registered agent base fee doesn't get you anything, other than complying with the law. You'd have to ask what cscglobal includes in their fees for "California registered agent".
In California, you'd have to file a Statement and Designation by Foreign Corporation form and pay $100 (cf. http://www.sos.ca.gov/business-programs/business-entities/forms/#fgncorp ). You should file that form with a copy of your certificate of good standing from the Delaware Secretary of State and you should be good to go.
Later on, you'd have to file a Statement of Information whenever there's a material change in your CA corporation (such as change of address or officers) or every 2 years at least.
Of course, a lawyer or an agent can help you with those forms, but there's really no obligation to have a registered agent or even a "service for process agent" in California.
You are technically correct that you need to have an agent for service of process in California, but since that agent can be yourself (as you point out), you're essentially not required to have a registered agent in the Delaware sense (meaning a Delaware-approved company that can act as such, not just anyone).
Is this the only information you thought was inaccurate?
Furthermore, if CSC Global is representing itself as a "registered agent" in California, I would say that they are misleading their customers, because they can't make that specific claim, as it could be construed as the same mandatory role a registered agent has in Delaware (they could say they are a California agent for service of process though)
Brian is right. I didn't check that Vishal is apparently based in SF so Inferess is by default doing business in CA.
In that case, the tax advisor shouldn't have _suggested_ to incorporate as a CA foreign corp, but _mandated_ to do so. At this point, it's not an alternative, but how you go about doing it is your choice. Brian's S&DC-SN form is really all you have to file at this point, along with a $100 check - add $5 if you want to get a certified copy, which is recommended)