Do I need to translate my US marriage license for an E-Visa application for Thailand?

No you can use it as is for the initial 90 day Non-O visa. But there are some hoops you need to jump through if you want to get an extension of stay based on a US marriage certificate, some of which are easier to accomplish while still in the US. You need to get it the certificate apostilled, then approved by the Thai consulate in the US. Once you reach Thailand you get it approved by the MFA then take it to the local Amphur where you live and they will issue you with a Thai certificate which you require to apply for the extension of stay based on marriage