What gets fixed automatically

Missing VTIMEZONE Adds timezone definitions for referenced TZIDs (Asia/Tokyo, America/New_York, etc.)
Invalid Timezone Names Converts aliases like EST, PST, JST to proper IANA names
Missing UID / DTSTAMP Auto-generates unique IDs and timestamps for each event
Line Folding Wraps lines exceeding 75 octets per RFC 5545
Missing Headers Adds VERSION, PRODID, CALSCALE if missing
RRULE Validation Checks recurrence rules for valid FREQ, BYDAY, COUNT, INTERVAL