There is at least one episode where written language was not translated by the Universal Translators in the comm badges.
In the TNG episode Contagion:
On the surface of Iconia, the away team cannot establish contact with
the Enterprise. Picard and Data attempt to make sense of a large
console in the Iconian control room. Data determines that the Iconian
language shares enough common roots with other languages to enable him
to develop a working understanding of the controls. This understanding
proves to be somewhat less than working, as Data's attempts to engage
"manual override" result in the appearance of a gateway. A series of
landscapes and architectures cycles through the gateway.
Clearly the language was translatable, but was not translated. The only difference is that this particular language was never spoken during the episode, and Universal Translators usually use speech to translate.
Although I too cannot pinpoint which episode Richard is referring to in the comments, I suspect that alien speech was heard during the episode, and yet the translation did not extend to the written language.
Then again, most of the time, people automatically know what alien tech does seconds after seeing it for the first time...
This can be probably chalked up to inconsistency and lack of foresight (using consoles as more than just set pieces)