Before grammatical pauses and especially sentence finally it tends to happen, yeah, and some speakers do it more and more consistently than others. It also happens with /v/ and /z/ a bit, and more rarely (not in this TTS I think) with /l/.
For these guys, it's not a complete devoicing (like, you can still tell the differences between sentence final /f/ and sentence final /v/, sentence final /z/ and sentence final /s/) These are not conscious phonological process for Turks, however, and so you see a lot of variability in accents and speakers.
Moreover, if you DON'T devoice nobody will misunderstand you or think you're wrong. I start unconsciously picking this up after ~3 years of Turkish I think (my first year living with natives). Sort of the same way my husband started picking up English word-medial /t/-to-glottal stops (words like kitten, mountain) after living among native speakers. Nobody ever told me to correct, and nobody thought he had bad pronunciation. It's just something you can pick up to refine your accent in time, but I don't think it's a good one to concentrate on at first.
Contrast these to the sentence final devoicing of stops and c in multisyllable nouns (b to p, d to t, ğ/g to k, c to ç) that happens consciously and grammatically. Those are the ones you have to concentrate on to be understood, and luckily they area consistently marked in written text as part of standard Turkish. The voiceless word final stops and ç will get voiced when a vowel follows them: kitap--kitabım (my book), ağaç--ağacım (my tree), etc. Saying kitap-ım will potentially not be understood. If you say ağaç-ım people will assume you're saying "açım" (I am hungry).
It's all English's fault, really. Turkish actually tries to minimize your use of articles, doesn't even USE a definite article. That's a language trying to do a guy a solid.
But English has to be all "articles EVERYWHERE with COMPLICATED RULES and even though it's super sophisticated, native speakers think it should be easy and think you're DUMB if you make mistakes."
So unfortunately, no -- you do have to think about it because articles aren't expressed in Turkish but have to be expressed in English.
The pronunciation of "Çocuk" sounds kind of as if the "o" is pronounced "front" like a German "ö" rather than a "back" "o." Is this understanding/interpretation correct? Is this a consistent pattern, that "o" in Turkish is always pronounced this way, or is this merely a case of context of this word/sentence?
The "r" sound in Turkish has the tongue approach the roof of the mouth but not quite touch, or touch very light and quick. Especially when "r" comes at the end of a word the tongue gets so close that the air coming over it makes a hissing sound like an "sh," and the vocal cords stop moving at the word's end (it's a devoiced r, that is), so it's harder to hear it as being a "r" sound.