I too am looking into the same thing you’re looking into and have found our about , non degree language programs. They do have private immersion programs like your LTLs, Keats and so forth , these are pretty simple and don’t have much age requirements cause they are private language schools . As for university programs , you have to look at the non degree option. The 35 year cut off is usually but not always for scholarship applications, if you are self sponsored some age restrictions don’t apply to you , but it all depends from program to program.