1.  The last of the examples at the end is obsolete -- it uses "2" for
the charset.
2.  The last of the examples is also *incorrect*.  When my software
decodes it, I get:
[** ISO-8859-1 charset **] If you can read this yo
[** 2 charset **]  the example.
Now, the stuff in brackets is what my implementation curently spits out
at a character set change, but I suspect there is ALSO missing data
here.  At least, I'm pretty sure this isn't a bug in my decoder causing
this problem, but I could be wrong.
Oops.  My face is red.  I ran it through my decoder again, and I got
the same results you did.  The example should read:
Subject: =?ISO-8859-1?B?SWYgeW91IGNhbiByZWFkIHRoaXMgeW8K?=
 =?ISO-8859-2?B?dSB1bmRlcnN0YW5kIHRoZSBleGFtcGxlLgo=?=
Keith