First the 'bad' news. What I see in your pics is that the turnbuckle is a closed "barrel" turnbuckle and the toggle-bolt is probably not a forged T-bolt but the infamous Taiwanese machined and screwed together T-bolts .... probably made by "Grand Deer".
How to ID these 'disaster waiting to happen T-Bolts': look very carefully where the threaded part connects to the cross link of the T-Bolt .... if the 'thread of the bolt' seems to 'disappear' into the "cross bar" and not tapered and blended to the cross bar as ***ONE SINGLE PIECE**** ...... the cross bar is
machined to fit the treaded portion of T-bolt assembly. If so you need to *immediately replace* the T-Bolts in their entirety, replace them with forged T-bolts ... and the strap eyes on the T-bolts.
These 'machined' T-bolts are known to *catastrophically fail* due to crevice corrosion deep within the 'bar' of the T-bolt. You can still use the old closed barrel turnbuckle ... but eventually plan on changing them out too next time you replace the rigging.
A good rigger will have replacement FORGED T-bolts and strap eyes. You might want to put a temporary stay (halyard, etc.), remove that T-bolt and take 'real good look' at it off the rig to help ID if it is in fact a non-forged / 'machined' toggle bolt. If a boat has one such t-bolt you probably have 'many' such machined 'exploding' T-bolts.
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As to the rigging 'anomalie', best way do to this is a new chainplate with a
double eye at the terminal upper end of the plate. The main load from the rigging shoud be as straight as possible into the plate proper - the auxiliary load 'can' be connected to the main plate as a smooth offset (an angular 'gusset'). Take a look in your harbor for any cutter rig that also has intermediate stays (Baba, Panda, Tashiba, Tayana, Valiant, Passport, etc.).... the intermediate stay usually always connect to the same chainplate that also connects to the lower aft shrouds --- a single chainplate with two 'pin connections', one for each stay.
hope this helps.
