Removal vs (current) Locks: I'm with
Laveley on this one. They're pretty much the same. They both do two things: give you some point value (in some combination of increasing your own and decreasing opponent's) and disable an engine. Neither of them are more "easy" or "interesting". There are different counters to them, like elimination can be countered with resurrection and buffing (usually it means handbuffing as engines tend to get insta-killed) while against locks the only counter is your own lock effect into unlock. But that's just technicality.
In general you want to add some kind of price to disabling engines, otherwise everybody just runs these type of cards in the masses and engines have no chance. Trick is to define a proper price. You make it too low, and they're almost free so again everybody runs them. Make it too high they become too weak against non-engine decks (aka swarm or "point spam").
In current state locks' price is too high, while you might argue that elimination's price is not high enough. Still if any kind of balance exists, it's a very delicate one, and I'm not convinced, that it's even possible. Maybe the best thing is just some weird rock-paper-scissor setup where engine beats point spam, point spam beats control and control beats engine.
But that problem holds true for both lock and elimination effects.
Alternative Lock suggestions in OP: while I find them flavorful, I don't think most of them give too much mechanically to warrant the introduction of a new keyword / effect.
- Freeze: this one I find interesting, temporary block versus complete disable may be good balance. But it needs to be tested as this temporary block may be just enough to render the engine effectively useless, so it wouldn't be too different from complete disable. It would also need to be properly priced, just like complete disabling with the same problems.
- Paralyze: so pretty much the same plus some damage over time as added bonus which has nothing to do the problem we're dealing with. I could see this effect on a specific card but it just makes no sense to me to include it as a separate mechanic.
- Stoned / Statue: so basically a worse Artifact Compression when it comes to engine elimination. But instead of finding alternative value against non-engines by dealing with high point enemy units, you could use it it to buff your own. Sounds interesting but based on how many points you add to the card I have a feeling it would be too weak against either engines or non-engines or just mildly unimpressive in both cases.
- Confused: very binary. It wouldn't create any value against non-engines or even against some engines like self-buffing ones. Other cases it would be just enough or insane value. So strongly against it.