Hi Rahula,

>How would you translate: Buddhoti yo so bhagavaa sayambhuu...

Not having studied that text, I believe it's a definition or
explanation of the term 'Buddha'. sayambhuu is an epithet of the
Buddha, see Sanskrit svaya.mbhuu, self-existent = Brahma, Shiva etc..

Maybe it could be translated like this:

"Buddha": that (so) fortunate one (bhagavaa) who (yo) is
self-dependent (sayambhuu)...

The text continues with further description of the meaning of the
word 'Buddha'.

best regards,

/Rett