With the current tech tree, it's possible to use a lot of Gleba recipes early: e.g. Bioflux processing gives recipes for plastic, rocket fuel, sulfur and lubricant which do not depend on any of the usual tech tree nodes required to unlock the "usual" recipes for these items. This seems somewhat reasonable, though perhaps a bit too easy (I've been abusing the rocket fuel to power my base, and using Gleba recipes for all my plastic and sulfur).

Perhaps Bioflux processing should become a regular research item using RGB + agricultural science packs to unlock?

In contrast, "tree seeding" requires space and Gleba science, making it inaccessible until significantly later. It shouldn't depend on space science in my opinion; planting trees is not that difficult!

The Vulcanus stuff seems better balanced since everything is locked behind the Tungsten carbide research node which already requires RGBP packs.

Are you playing without enemies? My thinking was the military requirements would gate it well enough.
But you do bring up a good point.

No, enemies are on, to the point I had to get some military research early.

Coal liquefaction is another recipe which feels a little unbalanced. (Or maybe it's just me picking a map without much oil nearby.)

Sorry for so little response, I have been wrapped up in the refactor for 0.12.0.

You hit on some interesting points and I will share my current thoughts, but I can be persuaded.
It was not my intended to modify the game, beyond the map generation and the few changes to make that clean and workable. On the mod page, I have:

The structure of the game changes, but the mechanics remain the same.
How much this matters depends on how the engineer chooses to play.

And you are touching this very topic. You do not need to take advantage of the compressed playing field. Using easier or better recipes for example. But you can, if you want to. Some people may want to use it for the very things you do not care for, to sort of jump ahead or take the easier/quicker route. Because their goal is to play a new planet mod, and they prefer the quicker routes to get to that new planet.

If I change technologies and recipes, this mod becomes less compatible and more headache for all.

Maybe I can add a startup option to help with jumping ahead. To rephrase in my words, you would like the vanilla technology progression enforced?

As for oil and coal, you are at the mercy of map generation. What is an issue for you on your map, some another map will have a glut. There are mods you can add to help with these, this complaint is as old as Factorio. :D

As for a mod suggestion, not to promote my own mod, but you can make a one time use of Ore-ganizer. Fight your way to where you feel is a legit location for oil, place down one of the Resource pumpjacks, fast-replace it with a regular pumpjack, then you can pickup the pumpjack and it will leave a crude oil spot. Make a few more and then uninstall the mod. And/or use a Resource mining drill to do the same for coal.

Thanks for the suggestions.

Choosing not to modify the tech tree in this mod is a legitimately decent option all things considered. Making optional changes in this mod or another (recommended) mod could also be an option. It's your choice what goes into this mod; I'm just making suggestions.

I think there are good reasons to consider deviating from the stock tech tree with this merged map generation that enables faster access to some other planets. Is it then accidental that rocket fuel is available through Gleba recipes much earlier than it would be through the normal stock tree?

Perhaps it could be an option that the first "planet" tech requires some amount of Red,Green,Blue,Space science.

Version 0.13.0 has been uploaded, it should resolve this issue. All technologies with the prerequisite of a planet discovery (Aquilo, Gleba, or Vulcanus), now have the prerequisite of space science packs. There is a startup setting, the default is disabled.