Castonguayh,
The Programming Forum might draw some additional insight to your problem but you will still see the same members (it's not a sectionalized forum, per se).
A couple issues I noticed while trying to duplicate your efforts:
I used Notepad and typed a simple sentence. I selected a character from an .htr file and it along with the Control window came into view.
I highlighted (selected) the sentence (drag across it), Right click and choose COPY (with the idea of doing a PASTE into the Control window). As soon as I selected the COPY, Hal's voice started speaking the selected text BUT the character's lips did NOT move.
Next, I saved the sentence as Test.txt in Notepad. Using Windows Explorer, I located the file and dropped it into the Control window. The Hal character spoke the sentence AND the lips moved.
OK...progress.
The sentence was about 8 words so I typed several more sentences until I had 130 words. Again, Saved as .txt file, locate and Drop into Control window. Perfect.
One more time only I copied the first paragraph and pasted twice, giving me 390 words. Saved, Drag & Drop into Control window. No problem. Boring to have Hal re-read the same text but Hal did not flinch while reading a 390 word text file.
I don't know what the practical limits might be until a memory overload issue occurs but for your proposed purposes, I don't see where several paragraphs of speech should pose a problem.
Lastly, which TTS voice (and company) are you using and are you using the free or paid version of Hal.
Hal is not setup to allow use of additional Haptek characters without the purchase of the Character Expansion Pack.
Just some thoughts. Keep us posted!