Hmm, i've taken a look at that paradox. But what if, the Titan Realm, which is timeless is the missing piece? Eren does not die and becomes the host needrd for time travel to still work.
Also another possibility is the time travel commonly known to us, and in the example shown in the link, points out time travel won't be possible, if he goes back in time and kills the grandfather. On the other hand, here i'm gambling on the fact that the Hallucigenia destroyed, will only stop new eldians from becoming titans after. Eren with the powers will go back in time and stop Ymir interacting with the Hallucigenia, OR if it does interact, not be transformed and abused by the Eldian Empire, this will then remove all the negative events that followed suit.