I can´t find any Informations about useing Interrail/Eurail on the FrecciaLink Buses

Would you share with us you brochure where you get this informations.

I even can´t find it in the PassBenefit section of Italy (Still can be possible to use the Bus with interrail as the Benefitspage are not 100% uptodate)

Certainly can, I found it here, all the way down on p.103: https://www.acprail.com/wp-content/uploads/Benefits-Brochure-Eurail.pdf

Admittedly it’s not an up-to-date source, but it does mention it (I assume the term Freccialink only ever refers to buses?). I was interested because Trenitalia run a service from Salerno to the fascinating cave city of Matera, which connects up with Frecciarossas from the north.

I’m quite optimistic that reservation might be included at no extra charge, because it says on the official website that journeys on them can only be purchased in conjunction with a train - which surely ought to mean that the traveller only pays one reservation fee because they are only making one booking. If that is the case, this could be a great-value option which slightly expands the list of remoter destinations for passholders in Italy.

I did not even know about these and have looked it up on their site. There are 2 types: a few to cities just off the HS-lines (Perugia) and only in winterseason and then not even daily, to a few winter/skiresorts.

There is a daft simple ALTernative: all of these cities (not the resorts) also have traditional classic trains by Tren Italia, but it may be a little slower.

In general though info on using IR/EUr in IT is years behind and not updated as one might expect-and is done by more client-friendly countries like DE/NL/SE etc. F.e. its still unclear if IR/EUr is accepted in some regione who have merged the trains from TrIt with a few of their own local systems, like TPER in Emilio-Romagna.

My bet is that they will be utterly surprised that someone with a pass might even want to go by these buses. And anyway-since a year or 2 REServations for Frecce trains must be done in person, shwoing the pass, at a counter. They will inform you. My bet is that as also every single train ride on a Frecce (=arrow, for the HiSpeed) needs a separate REServation and hence fee to pay, this will also apply to these buses. Perhaps a normal ticket may even be cheaper as the usual 10 eur charged.

I agree that most of these routes are a bit superfluous, but the particular one I mentioned, to Matera, does actually look pretty useful - particularly as I’m thinking of starting this journey in Rome, rather than somewhere east of the Apennines.

The only way to get into Matera by rail at the moment is by going all the way out to Bari and then taking a narrow-gauge train (non-IR/ER, but incredibly cheap) via Altamura, which would take quite a bit longer. I probably would do that for the next leg of my trip though, before taking the mainline up to Milan.

In any case, hopefully an IR staff member will be able to answer this question next week, but thanks for your input :-)

I asked Trenitalia and they said first the Railpass is not valid on these Services and after showing them the brochure they just tried it and as @mcadv  said they charge twice the reservation fee as these Buses have within the booking system a own “Trainnumber”

Thankyou @seewulf , truly above-and-beyond!