What other errors are there? Bech32 addresses are of a fixed length (42 characters for P2WPKH, 62 characters for P2WSH or P2TR), so any error which adds or deletes a few characters will immediately result in an invalid address. The checksum will detect any error which affects up to 4 characters.
well i mean maybe this is splitting hairs but you're not defining what your universe of errors consists of. i think they have a definition of what an "error pattern" is:
We define an error pattern as a sequence of first one or more deletions, then swaps of adjacent characters, followed by substitutions, insertions, and duplications, in that order, all in specific positions, applied to a string with valid checksum that is otherwise randomly chosen.so any error that does not fall into that particular definition is the answer to your question maybe.
The reason that Bech32 excludes the characters "1", "b", "i", and "o" is explained in BIP173:
The character set is chosen to minimize ambiguity according to
this visual similarity data, and the ordering is chosen to minimize the number of pairs of similar characters (according to the same data) that differ in more than 1 bit. As the checksum is chosen to maximize detection capabilities for low numbers of bit errors, this choice improves its performance under some error models.
so it's basically what i said. for visual reasons.