Last year we bought hose attachments for our toilets since we would be cloth diapering a new baby.
When performing the install to the toilet, I used a bunch of teflon tape (about 3 wraps on the threading) on the male end of the connection prior to installation. For the downstairs toilet, I had no problems, but the upstairs toilet developed a leak at the connection that was discovered late and caused a little bit of water damage. I don't recall any issues when screwing things back together other than it was an awkward angle (nothing was forced).
If it matters, the connection was metal to metal.
The leak wasn't present at the initial installation (or at least it wasn't obvious). I discovered it about 3 months afterwards when we saw some browning in the ceiling of the living room. Given it's the back of the toilet, the pitch of the floor in the bathroom, and the slow rate of the leak, it never flooded more than just a small 2 SF area behind the toilet.
I ended up removing the hose because we tended to use the downstairs one so much more regularly, but is there more I could practically have done beyond the teflon tape to improve the water seal?