Why didn't a time wraith attack Eobard-Wells?

The Time Wraiths' mission is to track down time travelers that abuse of the Speed Force and mess with the timeline.

But the goal of Eobard Thawne was to go back to his own era. For this to happen safely, he had to make sure that the changes to the timeline were kept to a minimum level. That's why he closely monitors Barry, trains him and manipulate rogues in order to make Barry fast enough to help him. He also constantly consults Gideon and checks the future newspaper to see if no major event had been altered.

There is maybe three events that have been altered during the 15 years Thawne had been trapped in the past:

1. Hasten the explosion of the particle accelerator: the show, and the sister show Legends of Tomorrow, has shown that there are some flexibility in how events unfold. LoT has the concept that a change in the timeline induces "time waves". There are small and big waves, with negligible to catastrophic consequences. Expediting the explosion is probably not a big deal: meta-humans still appeared, the Flash is there to fight the ones that goes rogue,...

2. Killing Harrison Wells. Since Eobard Thawne did his best to act as Harrison Wells, we can guess that it has limited effect to the timeline.

3. Obviously, the death of Barry's mother is seemingly the biggest one. Legends of Tomorrow bring the concept that some people have limited to no impact on the timeline. We may infer that Nora was probably one of them. After all, she was only a loving mother and the only consequence of her death was the imprisonment of her husband. Sad for him but not a history-changing event. Note that the Flash also existed in Thawne's timeline, so her death is not as instrumental as we may think in the decision of Barry to become a hero.

Why didn't a time wraith attack Eobard-Wells? dc the-flash-2014 the-flash In the CW series, the Flash, the concept of time wraiths is a little confusing. (I know it's kinda late to ask since Season 3 just finished), but I was wondering, why didn't a time wraith attack Wells-Eobard?

If you paid any attention to the show, especially season 2. You'd understand that Eobard Thawne is a walking bootstrap-grandfather paradox combined. He was always meant to create the Flash, though he didn't realize it until it was "too late" after he killed the real Wells. Hence you got the confession where he said they were never truly enemies. He truly understood he was always meant to create the Flash. On top of that he had some season 1 spoilers from Cisco and Barry obviously.

He stayed for 15 years in the 21'st century and was manipulating the timeline. Why didn't a speed force enforcer show up?

He didn't manipulate anything. He was only fulfilling his own role in the big schemes of the universe.

Was it because Eobard-Wells was integral in making Barry the Flash, to cement the very timeline? Was the Speed-Force allowing Eobard to live because he could create the timeline?

There was no timeline to be cemented. He has always been the creator of the Flash. He just didn't realize it until later.

Season 2 Barry to season 2 Eobard: You ruined my life. You killed my mother.

Season 1 Eobard to season 1 Barry: It is your destiny to lose to me, Flash. Just like it was your mother's destiny to die that night.

Another hint: Thawne was informed by Gideon that Wells successfully launched a particle accelerator. No mention of word 'explosion'. Furthermore, a successful launch negates the possibility of Barry gaining his powers in 2020. Gideon was feeding him bs on spot. That's why she was made by Team Flash.

I know that the concept of time-wraiths was introduced in Season 2, so no explanation was offered about this thing. But is there any other reason than it being a plot hole?

It's not a plot hole. That's why it happened. The only time Wraiths came for Eobard was when he was with the Legion of Doom.

Because Thawne "knows what he's doing"

The accepted answer is incorrect. In the Season 2 episode "Flash Back", Barry travels back in time for advice from Thawne on how to increase his speed. A time wraith shows up several times to attack Barry and is seen by Thawne who thinks it's after HIM until he realizes this version of Barry is from the future.

After capturing Barry, the following conversation ensues:

Thawne: Now, who are you? I mean, who are you really?

Barry: Dr. Wells, what are you doing?

Thawne: None of it adds up. The interference with the comms, the speed equation, the Time Wraith. That's what we call them. Time Wraiths.

Scary, aren't they? [chuckles] I thought, "Oh, no, a Time Wraith has found me." But then I thought, "No, no, no. You know what you're doing. Now, the Time Wraith is after someone who's traveled through time and doesn't know what they're doing."

_{The Flash S02E17 Script}

So Thawne is familiar with time wraiths but hasn't had any come after him because he "knows what he's doing".

We aren't given any further details on what steps are necessary to avoid their attention but what's important here is that there IS a way to avoid them and that Thawne has the right knowledge/experience to do just that. Barry doesn't.