HOP! - renting plane

[Opsa]

We are flying on HOP! this summer and received an email that the plane we're booked on will be replaced by a plane they are hiring from a Slovenian company. From online reviews, it seems this is not uncommon procedure - however, in light of the Salo incident, do I need to be concerned?
Can some pros provide reassurance?

[Hotel Tango]

It looks most likely to be a CRJ-700 or a CRJ-900 from Adria Airways (they have both). The airline has been operating since 1961.

[Duchess_Driver]

...with many companies providing what’s known as ACMI. Helps them through peak demand...

Cello had their Avto RJ on contract with HOP last year - which is possibly where the demand has arisen from due Cello going Tango Uniform.