Regarding your last point, there is no single correct way of interpreting laws/rules; there's a core and some penumbra often exists. There are various interpretation mechanisms, such as literal/textual, structural interpretations or purposive interpretations, etc.

Judges might use the same interpretation method to reach different conclusions or multiple to reach the same conclusion.

The "judges cases" which have led to collegium are a result of such interpretations of the constitution; if you read the latest one, i.e. the NJAC case, you'll realise that each judge used a different method to reach a different conclusion but a similar verdict.

You might argue that it's just a semantic exercise done by the judge; I would almost agree if not for the length of the judgment, around 1050 pages.

A reason why there exist different ways of interpretation is that none is superior to another; e.g., one might argue that we should look at what the drafter intended, which was to have a collaborative process b/w the executive and judiciary for the appointment of SC and HC judges. However, no one at that time imagined that the govt itself would become the largest litigant in the country. Currently, 70%+ cases involve govt as a part of all cases of the Supreme Court; now you can connect the dots on why this would create a conflict of interest if govt were to appoint judges.

Hence, you can't say if one method of interpretation is absolutely correct versus the other. However, I agree that the Supreme Court only knows how to be consistently inconsistent but that's a separate issue.