What are alternatives to l-theanine in action/effect mainly pro-social, anti-anxiety

Theanine is so mild it's difficult to pin down another that provides similar sensation.
I would suggest bacopa and kava kava, but Theanine is an amino, not an herb, so for that reason I'd say GABA

Relora. Far more effective for anxiety than theanine in my experience. Long term use, no tolerance issues, no tiredness. Works mainly to reduce cortisol

Other than what was already mentioned the basic thing to watch is Magnesium intake, ideally you spread the dose out over the day and use multiple forms to improve absorption. My mix (for price and quality) ends up as Citrate, Glycinate & Gluconate, some people swear by Threonate but its too spendy for me to bother yet, as long as its not Oxide you will get good enough absorption to help.

Can also vouch for Picamilon as being at least more effective than GABA on its own, doses should stay below 300mg for predictable effects however (the OTC form comes in 50mg tabs and 300mg is max recommended dose) as some people can get paradoxical stimulation above that. More used as-needed to relieve head pressure than a daily thing for me, great to dispel headache auras or ease the edge of stimulation along with Theanine. Never really noticed tolerance or withdrawal effects though even when using multiple doses a day.