So I’ve been reading through Athenaze, both the English & Italian editions, and I keep seeing ὅ written in place of ὁ when it is written before τε. Is this because τε is a proclitic and Greek consequently needs ὁ to be written with an acute so as to maintain the pitch-accent flow?
In general the word preceding an enclitic acquires an acute accent in its final syllable. See e.g. this article under the heading ‘Effects of enclitics’.
I suppose I could have also looked at my own textbook. Athenaze Book 1 says that when proclitics (and it lists ὁ and ἡ among them) are followed by an enclitic (and τε is an enclitic), they must be accented.