Having done some transcription from scans of parish records for the Kent FHS, I can see how 33 and 38 could be confused, especially in the early 1800s when so few people were literate. Some parish incumbents had handwriting that you wouldn't normally gratify with the name!
And there is always the point that Richard MIGHT just have lied about his age on marriage (a) to get around the consent rules as his father was dead and mother apparently on parish relief and/or (b) to avoid having to admit to his wife-to-be that he was still only a boy by comparison with her, and then was obliged to sustain the deception. Mary Elderkin would have been the informant for his burial, and she may well have believed he was the same age as her instead of 3-4 years younger.
It's still an anomaly, but one we are never likely to be able to resolve....in the meantime, given the quality of all the other research, I think - like Robyn - that I am inclined to accept Richard as my gggg-grandfather.
And thanks, John-P , for checking the original. I will also folow up the Charles witnesses.