You could achieve space savings with a larger dictionary, but it'd be at the expense of readability, which is already poor.
It might actually be more readable for people who know a language with a lot of characters to convert it into that. For example, if you start with a Base58Check-encoded Bitcoin address like:
1NYcRLuPCTd6Lamxf1mZTdpjo6ubs4pKL2
...you could plausibly turn it into something in Japanese like:
印可基 口合宗 出具隅 終上 占西前 杉獣淑
...which I think is probably an improvement. It's certainly easier to tell different addresses apart using that scheme than the original base 58.
But it's still too long to memorize or reliably type without screwing it up, and if you have to copy-paste the thing anyway it's not really obvious that it's helping with any actual problems.