Positive talks is a good start. There's no reason why this can't be resolved in a productive way... except the usual Rugby League stuff of egos, control, and fighting for scraps.
From what we can gather, the E13 idea is:
Existing clubs from around Europe, with players from their nations.
Central draft of higher level players paid professionally with the rest being Amateur - Semi-pro players.
Cup Knockout in year 1, full League in year 2.
Gradual expansion/growth with the aim of being in the same ballpark as the existing 2 major comps.
The RLEF discussions seem to be targeting more of a "Super League" idea,
with new clubs in major cities chosen for strategic and financial value.
Other details are unknown but you would assume they are more or less similar, as it will be impossible to be fully professional straight off the bat.
I think there's some decent compromises and the bones of a good comp here.
Firstly, around governance. EuroXIII could be the competition body sanctioned by the RLEF, but the RLEF has to make some money out of this.
Secondly, around teams and locations. I support using existing clubs, but there should be a strict criteria on locale branding and suitable stadiums. Example, lets say Lillestrom Lions apply from Norway. Their application would be dependent on rebranding their first team as Oslo Lions and have a suitable city location. We have to look bigger than small towns. Internationally known regions or cities.
We start with 1 team per country, and that team becomes the high level pathway between the national team and the local comp. Ideally, local comps grow in size and quality as a result.
I would stick to continental Europe. UK and Ireland clubs should push the RFL if they want to play at a higher level.
On growing and expanding the competition, some nations may be given more than 1 team, similar to the Champions League, on the basis of their domestic playing numbers and quality. It would be obvious that France may have an extra team quite early, and Serbia and Greece may follow.
It is crucial that regardless of format or governance, there needs to be financial and broadcast backing, and the competition must have a professional image, even before professional players. Without this, it is a novelty. As good as the USARL and BSL are, they struggle with consistency and growth because there is no money involved. Same goes for the European Cup.