Dear Birgit,
Thank you for your valuable notes. Perhaps I should've written a follow-up email to this in good time.
My friend Kazuo Kano came to the rescue -- and this is certainly not the first time! Apparently the plates were passed on to Wogihara, and later ended up with Kendai Eno'u (if this is the right spelling), who published it in 1973. Nagao wrote a review in 1976.
The text is indeed called Prajñāpradīpāvalī (actually, this is only a part, the 8th chapter), just like its Tibetan translation, which is attributed to Jñānapāda, but these are two very different texts!
At first I thought that this must be the 'other' Buddhaśrījñāna, who worked among the Gnubs, but then I started seeing quite exact parallels in Abhayākaragupta's Munimatālaṃkāra (and therefore in Daśabalaśrīmitra's Saṃskṛtāsaṃskṛtaviniścaya). I'm still not quite sure, but chances are that this could be (a bit of) one of Jñānapāda's juvenilia, composed after his study with Haribhadra (whose influence is undeniable), when he was at Nālandā, before his (first) trip to the Konkan.
Is Merī jīvan yātrā online by any chance? It would be wonderful to read it, not only for 'our' interests, but also because it's considered, if I understand correctly, the foundation of the Hindi travelogue.
Many thanks once again.
Yours,
Peter