A few things.
First, there are such strong biases toward finding planets very close to their stars that an Earth-like planet around a Sun-like star is still a big reach. That is, only one (Kepler-452 b) has been found to date. But Kepler can't do this anymore, and radial velocity can't find a 10 cm/s amplitude signal at 1-year period. So, from that point of view, finding your planet in 10 years is doubtful just because it's hard.
Second, you way overestimate the power of the next generation of planet-finders. Of the ones you listed, only PLATO is capable of finding planets on Earth-like orbits (WFIRST maybe in certain cases but only for a statistical sample not any individual star). But PLATO 1) is, sadly, likely to end up being significantly less powerful than proposed due to budget issues, and 2) isn't scheduled to launch until 2026 at the soonest. Plus, to find a planet at 1 AU would require several years of observations so you're looking at 2030 at the earliest and then only if lots of things go right.
Third, it's actually extremely hard to detect 1-year orbital periods. This is because it's easy to introduce an artificial signal into data with certain characteristic frequencies (especially 1 day and 1 year), so astronomers are very skeptical about planets with exactly those orbital periods. So, your planet could effectively be hidden in plain sight, but have been filtered out of the data. (This is more true of the radial velocity method than the transit method but it could still happen).
Given these issues, your planet could be right next door to the Sun, even orbiting a very bright star, and we would almost certainly not find it before 2030 at the earliest.
To make your story plausible, I would push the timeline back 20+ years.
Also, just to emphasize my point, please note that I'm an astronomer who works in part on searching for extra-solar planets.