if we here already.
The suggestion. Bad one, but who knows?
All planet type changing projects removes conditions that new type can not host and add conditions it can not exist without (temperature, atmosphere), but do not add recources it can
potentially have. In other words, if you terraform barren into terran, it will gain normal temperature, atmosphere but not farmland, volitiles or organics. You have to improve that with a separate projects, similar we have "mild climate" now. Those projects always increase those values by 1 (not above maximum, ofc.) or add minimal amount if there was no of it.
Projects can be applied even on non-terraformed worlds, that have those resource values below maximal to it type. Example: You have desert planet with no farmland at all, so you can add it with project, so it became "poor farmland"(-1). IIRC maximal farmland for deserts - adequate(0), but could be wrong here, so you can launch that project again, but only once. When you have this farmland (0) desert world, you can terraform it into terran, and farmland (0) will remain intact, so you need two more farmland projects to reach "bountiful" resource level.
1. Yes, it will add additional steps, players not always would like to do and confused of it. Serious weakness.
2. It makes more options for terraforming inside existing planet type, alongside with "normalize temperature" and "normalize atmosphere". Serious plus, especially if it is non-standard type.
EDIT: numerous Typos.