I assume that some of the more desirable artifacts are only available through Reward Points? (or is it "possible" to acquire a terraforming device, for example, through cashing in on the artifact accumulation)?

All artifacts, with the exeption of mission and NPC reward artifacts, can be aquired through artifact points.

I don't see energy cubes on the artifact pull list either (unfoirtunately).

I personally have recieved an energy cube and a terraformer since the latest change.

The only place I have ever seen an energy cube is on the Daily Reward (and it is rare). If it's available anywhere else, it's so rare that it's non-existent for all intents and purposes.

i have had two energy cubes in the last 5 or so days from the daily reward

What's the secret? I've seen it maybe 2 times in 67 levels (having played almost every day - it only takes about 2-3 minutes to spend all energy).

no secret, i just clicked on it beginers luck

rare artifacts are RARE. cubes come maybe once every week or two for me. if youve only gotten 2 in 67 levels, are youre unlucky. i try to keep my my production levels at 1 min per 2 artifact and 2 research. currently at 500 min, 1200 art and 1000 res at level 108.

Finding QSE / Terraformers / planet Flux / Ice Melter / Cubes with Artifact points is a joke now.

I personally never found a single QSE. And I've been playing for a while ^^