Here's the update.

*Tried calling twice for different dates in June that I found availability in AV and NH site. TK side couldn't check any availability for these dates in first, only in business and economy.
*Then tried for within-14 days range for curiosity and another agent was able to spot the availability. However, I was told that the ticket cannot be even held and have to go directly to sales office to do all necessary arrangements. Also was unable to quote me the amount of tax or even confirming me how many miles required (said approximately 43,000 miles for FRA-DEL, which he said could be more, or could be less ).

Conclusion - Looks like M&S system only shows up till 14 days in advance, just like before. At least it's still bookable, but as earlier posts suggested it's doesn't look like an easy process.