You derived citizenship automatically as a child based on your parents citizenship and other necessary criteria. But you didn't obtain a US passport automatically -- you or your parents had to submit a translated birth certificate (along with the official non-English certificate) with the passport application.Back then, mid 90's, if you were under 18 and your parents or one parent became a citizen, you did too just for being their child and didn't have to go through anything (assuming you were a resident which I was).
That means the passport authorities made a mistake by not asking for the English translation, or your birth certificate has enough English wording on it so the translation was unnecessary. For example, this Puerto Rican birth certificate has wording in both English and Spanish: http://columbianewsservice.com/wp-content/uploads/2010/04/birth-certificate.jpgI asked them, I never had to submit a birth certificate for translation, but they both did.
If you need a birth certificate when applying for something with a US government agency, it will have to be an English-translated birth certificate unless it has enough English wording like the example I linked above. A retroactively changed birth certificate is totally unnecessary; you'll use the same old birth certificate with your original name along with the name change court order.Because I changed my name legally in the courts when I got older, I don't want to translate my birth certificate, it could just create more confusion. Retroactively changing one's name on a birth certificate is something I'm not interested in doing as well.
There's no English on my birth certificate, it's entirely handwritten in Spanish. From what I've been told, it was never required to have the birth certificate translated to obtain citizenship via my parents, only the green card was necessary.
So you're not really worried about getting a translated birth certificate, you're mainly worried about your original Spanish-language certificate because it doesn't look official enough? Is it really entirely handwritten including the headings and standard text? If yes, I can see why you would be concerned.
The embassy of your birth country might be able to get a modern one issued for you (in your original name). You probably won't need it more than once in a decade, or maybe never, but it can take weeks to be issued so if you're in a situation where you need it and you don't already have it, that could be problematic.