About an hour ago user Paebbels went on on a tagging spree for "Lattice" (The PLD manufacturer) so of the "TOP QUESTIONS" about half are about Lattice parts, this seems undesirable because a small percentage of electrical engineering is PLD's and a very small percentage of PLD's are Lattice. Does this work itself out? Because right now this looks more like "Lattice stack exchange" than "Electrical Engineering Stack Exchange"
No, this is not desired behaviour. Users are requested to do these kinds of edits in small batches, to not flood the front page.
There are several feature requests concerning this, for example this one.
Out of courtesy to other users, large numbers of tag edits should not be done all at once.
That being said, yes the system is working as intended(people noticed the addition of the new tag). Tag edits are still edits, and benefit from community review. A few hours after this post, there were none of the mentioned edits visible in the active list.
Any edit of a question changes the activity value of a question. Any activity of a question will push it to the top of the active question list, the default sortation of the front page. That is by design.