No, there is no general discount on TER which would apply on multiple regions.

That said, about your Lyon-Marseille example, Illico discounts offered by Rhône-Alpes region explicitely mention that they are valid on that TER under some conditions. See e.g., Illico Annuel:

###Conditions parcours interrégionaux :

• Vers Bourgogne, Franche-Comté et Provence-Alpes-Côte d'Azur
• Abonnements vendus en Rhône-Alpes et sur support papier (pas sur carte OùRA!)
• Billets avantages (réductions autres trajets) possibles uniquement sur les trajets en Rhône-Alpes

which translates as:

###Conditions for interregional routes:

• To Burgundy, Franche-Comte and Provence-Alpes-Côte d'Azur
• Only for paper-based subscriptions sold in Rhône-Alpes (not on the OùRA railcard!)
• "Billets avantages" ([discount on trips not included in the subscription]) possible only on routes in Rhône-Alpes

No, there is no general discount on TER which would apply on multiple regions.

That said, about your Lyon-Marseille example, Illico discounts offered by Rhône-Alpes region explicitely mention that they are valid on that TER under some conditions. See e.g., Illico Annuel:

Conditions parcours interrégionaux :

• Vers Bourgogne, Franche-Comté et Provence-Alpes-Côte d'Azur
• Abonnements vendus en Rhône-Alpes et sur support papier (pas sur carte OùRA!)
• Billets avantages (réductions autres trajets) possibles uniquement sur les trajets en Rhône-Alpes

which translates as:

Conditions for interregional routes:

• To Burgundy, Franche-Comte and Provence-Alpes-Côte d'Azur
• Only for paper-based subscriptions sold in Rhône-Alpes (not on the OùRA railcard!)
• "Billets avantages" ([discount on trips not included in the subscription]) possible only on routes in Rhône-Alpes

No, there is no general discount on TER which would apply on multiple regions.

That said, about your Lyon-Marseille example, Illico discounts offered by Rhône-Alpes region explicitely mention that they are valid on that TER under some conditions. See e.g., Illico Annuel:

###Conditions parcours interrégionaux :

• Vers Bourgogne, Franche-Comté et Provence-Alpes-Côte d'Azur
• Abonnements vendus en Rhône-Alpes et sur support papier (pas sur carte OùRA!)
• Billets avantages (réductions autres trajets) possibles uniquement sur les trajets en Rhône-Alpes

which Google translates as:

###Conditions interregional route:

• To Burgundy, Franche-Comte and Provence-Alpes-Côte d'Azur
• Subscriptions sold in Rhône-Alpes and in paper (not on map OùRA!)
• Tickets benefits (discounts other trips) possible only on routes in Rhône-Alpes

No, there is no general discount on TER which would apply on multiple regions.

That said, about your Lyon-Marseille example, Illico discounts offered by Rhône-Alpes region explicitely mention that they are valid on that TER under some conditions. See e.g., Illico Annuel:

###Conditions parcours interrégionaux :

• Vers Bourgogne, Franche-Comté et Provence-Alpes-Côte d'Azur
• Abonnements vendus en Rhône-Alpes et sur support papier (pas sur carte OùRA!)
• Billets avantages (réductions autres trajets) possibles uniquement sur les trajets en Rhône-Alpes

which translates as:

###Conditions for interregional routes:

• To Burgundy, Franche-Comte and Provence-Alpes-Côte d'Azur
• Only for paper-based subscriptions sold in Rhône-Alpes (not on the OùRA railcard!)
• "Billets avantages" ([discount on trips not included in the subscription]) possible only on routes in Rhône-Alpes