So used a plain sans-serif (Gill). The original index label also did not use the ornate wordmark (in gold on inside of the lid), but a simple sans-serif text.
Too late for the mocked-up index label for the carrying case; but now here on the web an old style Linguaphone wordmark taken from the sleeve in a clean image file. Will probably still be drowned out by the more recent logo in a web-search, but there is at least 1 image file online now. Maybe for a next project :)