Familysearch has a Peter Malcolm born 15th MArch 1749 at Kilmany of John Malcolm and Jean Stewart- Kilmany is just 7 miles NE of Monimail evidently.
There are no Malcolm children baptised at Monimail 1730 - 1755, so it looks as though the family weren't from there. Familysearch have the film of Monimail - no 1040338, which should be viewable on-line. Have you seen the marriage entry and those of all the the children? You really need to check the actual entries in the registers if you haven't already done so.
Is there any other information such as place of abode? Occupation? Does it tally with the occupation you have in 1841?
John Malcolm married Jean 'Stuart' 18 April 1734 at Collessie, just a mile from Monimail. Again, you should look at the entry in the PR.
It's not really 'difficult from Oz'.
Scotlandspeople is the site to search the scottish parish registers. Pay to view each birth, death or marriage.
Or you can see them on familysearch, free. Go to 'catalogue' at the top of the page, and enter the name of the parish. when found, click on 'church records'.
I would disagree with you that the 'IGI' was more useful in the past.
Just not so. At least now you get actual, factual data, and not something somebody has made up out of thin air as half the IGI used to be. And you can view millions of films of parish registers, and other things, for free! Some at home (you need to b logged in - very easy, and again free), and some just at a family history centre. They will have them in Australia - I go to several in New Zealand.
Some films not yet digitised, but they promise they all will be by 2020.
, but I have managed to find dozens of my scottish people via this route - I would never have got them all through SP, plus you can pick up other titbits when you can view the whole registers sometimes, which you'd never find by just viewing, say, the birth record of one of your ancestors.
Happy hunting!