I don't want to encourage any conspiracy theories, but on the topic of incentives, there are a few at a higher level than the government employees you're thinking of.
One is that a number of governments, including the US, UK, Canada, and Australia, issue bonds linked to inflation. That is, as I understand it, they return a fixed amount over the measured inflation from some index. In other words, understating inflation would reduce the borrower's (the government's) payments.
Another is that Social Security in the US (and maybe similar things elsewhere) is periodically adjusted for inflation, so that the recipients don't lose purchasing power. Again, if inflation were understated, then the government would save money.
There might be other incentives to overstate inflation; the above is just what came to mind, so I am not implying that there is an overall pressure to understate inflation like people tend to claim without evidence. I wouldn't think there are that many inflation linked bonds compared to regular ones.
Ideally the people at or near the top who may have incentives to distort things cannot do it because the low-level bureaucrats keep on doing their jobs. But it hardly seems guaranteed at all times in all places.