At International level, Bruno Fernandes has 2 goals and 3 assists in 1048 mins (12 starts 7 sub) - That's a goal or assist every 210 mins approx. He has played against: Spain, Netherlands (2), Scotland, Luxembourg (2), Lithuania (2), Algeria, Switzerland, Serbia (info from Transfermarkt
https://www.transfermarkt.co.uk/bruno-fernandes/nationalmannschaft/spieler/240306/verein_id/3300 )
Jesse Lingard has 4 goals and 3 assists in 1484 mins (14 starts 10 sub) - A goal or assist every 212 mins. He has played against: Spain (2), Netherlands (2), Croatia, Italy, Nigeria, Slovenia, Malta, Sweden, Colombia, Panama, Tunisia.
Lingard is currently a completely useless PL player. Bruno Fernandes is an outstanding player in a weak domestic league with tons of teams that are somewhere between lower Championship and top of League One level, packed full of free transfers and loan players (see Transfermarkt for incoming transfers of relevant clubs).
When Fernandes played in Serie A, he didn't seem remotely special. Sampdoria sold him for less than £9m, in the summer of 2017. He started 79 matches in Serie A, scoring 15 goals with 14 assists (he took 2 pens, scoring one, direct free-kicks, indirect free-kicks and corners). His shot map for his last 3 seasons in Serie A is towards the bottom of
https://understat.com/player/1228 - 4 goals from outside the box, 26 shots saved from outside the box, hit the woodwork once from outside the area, 52 off-target shots from outside the area, 24 blocked shots from outside the area. So it took over 100 shots from outside the area to get 4 goals in Serie A. If anything, PL keepers are likely to be superior to those in Serie A. Spectacular goals in Liga NOS might simply result in a PL keeper conceding a corner.
If you look at Lingard's productivity in CL, PL, Europa League and domestic Cup competitions during his time at United, you will find that his output is noticeably better in the Europa League compared to CL and domestic Cup competitions relative to the PL. Even when he has been struggling to have an impact in PL matches, he has been able to get goals and/or assists in domestic Cup games. Drop down a level and it is easier to score and assist.
The fees being mentioned are absolutely ridiculous. There is a serious risk that Fernandes hasn't changed that much from his time in Serie A. At Sporting he takes on huge responsibility. At United he would be expected to be a team player. He will only take direct free-kicks and penalties if he is the best at them in training, and even then it might take him a while to be given the opportunity. He is not the main man for Portugal and his productivity reflects that.
This should be a modest fee, modest wages deal, or else let another club take the risk. United have a limited amount of money to spend. We need to spend it wisely. Being a better player than the current Lingard or Mata, is not a sensible justification for using £50m, possibly more.