I would like to ask you can give some examples of your own or from any source about using this structure with INDICATIF. I heard it is not always used with subjonctif. But I cannot find proof to substantiate this.
Might you help me?
There are other examples of the underlying structure "Il est à X que..." that do not take the subjunctive - for instance "Il est à noter que..."
I'm not exactly sure if this is your question, though. My understanding is that things à souhaiter are always in the subjunctive. As a phrase, it has even more uncertainty in tone than "Je souhaite que..."
Lucas-sp is right, subjunctive in French is not only a matter of sentence construction, it is also a matter of meaning. With uncertainty followed by "que", you must have subjunctive, whereas "il est à noter que", no uncertainty, no subjunctive.