If Soraka is in your base, other units in base are killed, are they safely healed and exhausted, even though there would be no change in location for the "Recall"?

Yes, Soraka, Wanderer will successfully save those units.

According to RiftJudge FAQ #1171, Soraka’s ability functions at your base just as it does at a battlefield. When she is at your base, units at your base are considered "here" and are valid targets for her replacement effect.

How the Interaction Works:

1. Replacement Effect: Soraka’s ability is a replacement effect that intercedes when a unit would die.
2. Execution: When a unit at your base would die and meets the criteria (friendly, less Might than Soraka), Soraka's ability replaces the "die" event with: "heal it, exhaust it, and recall it."
3. The "Recall" instruction: While the unit is already at your base, the "recall" instruction is still part of the replacement effect's mandatory execution. Per Rule 450, a recall simply relocates a permanent to its base. Because it is already at the base, it remains there. The fact that the location does not change does not invalidate the replacement effect; the unit is still healed and exhausted as instructed.

This is consistent with the general principle that replacement effects fulfill their instructions to the best of the game's ability even if certain outcomes (like movement) are redundant.