Ancient toponimy

Ciao, I'm Antonio from Italy (currently from Switzerland), I'm 31 years old.
I'm mainly interested in ancient toponimy of Europe (and romance toponimy
of my area, the Abruzzi region, Italy) and hope to find some feedback in
your group
It's the first time I post a message.
A question I would like to submit is: do you agree with the existence, of
an IE language responsible for a large number of place-names all over
Europe but different from the historically known languages (Celtic,
Germanic, Illyrian for what we know about it, Italic languages etc.). The
evidence of such a language (or people) was first proposed by Krahe that
called it alteuropäisch (old european) and recently recovered by F. Villar
(antiguo europeo).
It should be a language without distinction between /a/ and /o/, as several
IE languages but in contrast with celtic, latin, osco-umbrian etc.
Several river-names are reconducted to this stratum, for example those
showing the stems
*ad- 'stream' (Adua fl., Italy), *ais- 'rapid' (Aesis fl., Italy, Aeso,
Hisp., Aesura, Brit.), *al- 'flowing' (Alauna fl., Brit., Alentus fl.,
Italy), *al-to- 'flooded' (Altos fl., Illyria, Altinum, Italy) etc.
This stratum is usually invoked when :
i) the name could have an IE etymology but the historical languages cannot
explain certain phonetic or morphologic features of the name
ii) the name does not contain certain appellatives that are recognized as
typical of specific languages (e.g. -dunum for celtic, -burgium for
germanic, etc.)
iii) the name contains certain stems as the ones above that are so widely
spread across Europe and without substantial modifications, that cannot be
attributed to different languages