These days my biggest thing is teaching Spanish L1 speakers the difference between long-tense and short-lax vowels. For instance the difference between German Bett [bɛtʰ] and Beet [beːtʰ] or Lotte [lɔtə] and Lote [loːtə].

If you don't have a feature in your L1, it is a pain in the arse to learn it in any L2.
If some L2 contrasts features which your L1 doesn't even have, the pain grows even worse.

Esperanto is supposed to be accepting of all cultures and languages isn't it.

Well Gareth, Esperanto is just a language. It seems too restrictive to require its speakers only to express favourable opinions about other languages or cultures.

And it is after all a basic tenet of the movement that other languages are not suitable for the role of lingua franca.

robbkvasnak:I have been trying to acquire Mandarin. One of the biggest obstacles is the stupidity of Taiwan, Singapore and Hongkong who insist on using the old characters and sometimes the Wades-Giles (or yet another) transcription. They should just accept the fact that the majority of people use the simplified characters and the standard is Putonghua. It is even more confusing than the old fashioned British spelling and British irregular verb conjugations in English.
In Mandarin this makes everything super confusing, especially if you don't live in China and the native speakers with whom you can talk (in language class) insist on using their out-dated forms - which also exist is several variations. It is too much information with too many exceptions for the beginner. They are so steeped in their political convictions and their antiquated poliitical biases that they are defeating the whole purpose for the foreign student. I could, in deed, one day learn the old characters but first I have to stand on one leg.
When I teach English, I teach my students the easier American versions and point out the other irregularities. If they want to later study these specifics, they will atleast be able to feel confident in what they do know.

And here I am, upset by the fact that Hong Kongers write in Mandarin when the language they speak is Cantonese. I hope to see the day when they finally bloody write in the language they speak, i.e. Cantonese. While Cantonese is sometimes written, like in some comics, most of the times Mandarin is used. I find this ludicrous, it's like speaking French but writing in Romanian. I generally prefer the traditional version of hanzi, since I speak Japanese it must be why, but some simplified ones are nice, like 会 instead of 會 (thouth JP is rather a mix).