There is a committable config workflow, which also solves the “which ones did I change and how do I revert” problem directly: stalwart-cli snapshot Jmap Imap Http > baseline.ndjson gives you a git-committable NDJSON file of those settings, and stalwart-cli apply baseline.ndjson reconciles the server back to it. So the pattern for a migration is: snapshot those objects, raise the limits, run Vandelay, then re-apply the snapshot to restore the exact prior values. No remembering required.
The limits most likely to bite a Vandelay import (it runs over JMAP) are on the Jmap object (maxConcurrentRequests, maxConcurrentUploads, setMaxObjects, maxRequestSize / maxUploadSize) and the Http object (rateLimitAuthenticated); raise the IMAP ones (maxConcurrent, maxRequestRate) too if you import over IMAP. You can also import using an administrator account where none of these limits apply. See: Exporting server state | Stalwart, Jmap | Stalwart and Http | Stalwart.