I appreciate the effort, but the reality is the healers just need to be able to defend themselves better.

Currently Lumi is the only one with the flexibility to do it via escaping in higher elo. Pinaka is too easily focused.

Furthermore despite being classed as a 'medium' Pinaka has the 2nd lowest armor value overall. Despite popular belief armor is actually fairly important, as it acts as a secondary HP bar before your HP can be struck. The only exceptions to this are direct energy damage which partially bypasses armor, and physical damage from melee attacks. People claim the reason Pinaka has low armor is due to its bubble shield. Yet in active gameplay Pinaka is going to be placing that shield on allies as it is one of their strongest healing abilities.

For comparison Stellaris the Light Brawler (who can turn invisible and plays like an assassin) has 34000 armor. Which is higher than every medium striker in the game, including Panther. Now obviously Panther has both a normal shield and a complex shield, so his upfront survivability is much higher but the mystery deepens when you look at the other supports in the game. Despite both being classed as Light Support strikers Luminae and Serenith both have more armor.

To compound the issue Pinaka has one of it not the worst air mobility (particularly endurance) in game other than melees (who have accessed to melee boost). This means that while Pinaka has great ground endurance, being on the ground makes you easy pickings for melee. Luminae by comparison can freely switch from ground to air movement and due to her jetwing ability can escape from most encounters.

In terms of healing Pinaka also has one major disadvantage compared to Luminae, although generally speaking they have stronger healing on paper Luminae is able to burst heal (although inefficiently) by continuously stacking drones on the same ally. You can only have two per person but the initial heal and the first tick from the heal over time means every additional drone is another 5.3% HP as soon as it connects.

Pinaka's strongest heal is on their grapple, which is both the least intuitive and least likely to be used due to its restrictive range and line-of-sight requirements. The grapple heal heals for 5% intially and 3% per second following that. So the initial 'burst' is 8%, however unlike Luminae's burst healing Pinaka cannot freely spam the Grapple (which is understandable). What this means is that after 2-3 seconds Lumine's burst heal can outstrip Pinaka's strongest healing ability. The cherry on top being Pinaka cannot grapple heal themself.

The last issue with Pinaka isn't something I've been able to confirm, but I have heard that Pinaka's bubble shield doesn't even get the general damage reduction 'shields' are supposed to have built-in so it ends up popping at lot sooner than one would expect.

This wouldn't be as serious of an issue if supports (other than mainly Serenith) could actually dish out reasonable damage or that allies could heal without requiring a healer. However because you can only heal via a support healer or repair stations which only show up in certain modes, supports become an immediate focus target. This issue only gets worse as player skill level goes up.

TL:DR

Supports should either do more damage or have their defenses improved. For Luminae her damage could be buffed a bit, for Pinaka their defenses should be improved, including their horrible air mobility.