The line from Interlaken to Spiez is closed with replacement buses running. It is those the interail planner shows as not in network, this is incorrect, these are valid with your pass.

The direct TGV from Swiss stations have very high reservation fees, instead of this take the same route via Basel SBB by travelling to Strasbourg or Mulhouse by unreserved TER and catch TGV from there which costs less.

Which train is not included? The plannet of Interrail /Eurail is often faulty.

The following route might be suitable: Paris-Strasbourg (or Mulhouse), Strasbourg (or Mulhouse) to Basel, Basel-Interlaken.

No reservations needed for the latter two trains. That way you minimise reservation cost. 

See this topic too: 

Edit: for the 4th there are train replacement busses from Spiez to Interlaken due to engineering works. These are included in your pass. 

There are engineering works between Interlaken and Spiez so Interrail wants you to take a bus (not included) but there are rail replacement buses (pass valid).

Do not take the direct TGV from Basel as it has a 37€ fee (2nd class) or 70€ fee (1st class). Instead cross the border by regional train and then board the TGV.

Here is a route that would work :

- Interlaken Ost - Spiez 08:10 - 08:45 rail replacement bus

- Spiez - Basel SBB 08:54 - 10:32

- Basel SBB - Strasbourg 10:51 - 12:09

- Strasbourg - Paris-Est 12:19 - 14:02 10€

It looks like the replacement buses are not yet in the latest update of the rail planner app, which is about 1 week old. The cause is often a combination of those timetables being available quite late in the European Timetable Centre and the low update frequency of the rail planner app. And that's why it should never ever be used to plan.

Yes exactly. At least it's already on bahn.de (and sbb.ch obviously)