On the latest build, the following feature is broken

set vpn l2tp remote-access authentication require {value}

Setting this option should adjust the authentication options in the generated file at /run/accel-pppd/l2tp.conf
however, it looks like the template vpn_l2tp.xml.in and vpn_l2tp.py is broken.

There are references on line 103 and 111 in vpn_l2tp.py to if conf.exists(['authentication', 'protocols']):
but as per template definition I think it should be
if conf.exists(['authentication', 'require']):

Also, the way the code is written it looks like it would always include auth_mschap_v2 with no way to disable it.