I've looked now at original registers for Andreas, German & Jurby and done my own full transcriptions from the first two - the IGI is in parts a total mess - (a) it does not discriminate between verified transcriptions from the Parish Reg and 'anything' submitted by users - that anything can be total invention (anything marked 'sealing for the dead' usually is)
(b) the original basis for the manx IGI was the 1911 transcription done (or called for) by the Rolls office - it is this that is usually found if you see a C00xxxx batch number etc - however this transcription, though very good (especially so for Manx names, less so for singleton/non-manx names) has some errors and omissions (usually those where the date was given as a feastday or by ref to another entry)
(c) HOWEVER though it had this excellent basis the IGI has deleted such entries and replaced them by supposedly 'patron submitted' entries - for some parishes I believe these are re-transcriptions done in Utah and suffer from readers not familiar with Manx registers (eg the nonsense entries in which the residence was taken as the surname) - many of these entries have 'about' but the actual entry in the register is usually very clear - however there is another set of wholesale replacements where the IGI has taken some family submitted material and deemed this more accurate than the parish reg transcription - eg in German all Crellin, most Christian and Kelly entries are so treated