You say "realistic" then start off with a Spooner for Beaulieu trade...

Also it will be suicide if you start the season with Mitts as your 2C

Not sure COL would need Lehner, so I don't see that going anywhere.

We're not getting nearly enough value for ROR

I will give you a break since it is only your 2nd published team.

A few general ideas to keep in mind as you are putting together teams:
I posted most of this on an early published team but I think it is appropriate in this case as well:

I am going to give you a pass on your 2nd published team as it takes awhile in order to get the feel for this task. It is not easy and I am not very good at it.

A few general points on developing a team:

1. It is never a good approach to be throwing a plethora of players into a deal..... quality over quantity is the best approach;
2. No team is going to want your marginal players;
3. A bottom 6 forward or bottom pair D man is not very enticing;
4. Do not just guess or throw a dart when signing your RFA's or UFA's try to research the market to see what the market would determine that players contract value;
5. Try to look at every trade from the other teams point of view..... do the players you are trading to them make sense on their team, organization, salary cap, term & positional aspect;
6. If all a team is going to receive is a 3rd Round draft pick or less that is not adding much value to the deal;

On to your team:

1. If all the Sabres are getting for Lehner is a 5th Round pick they will keep him and not even bother looking for a FA goalie;
2. Grubs is not right for the Sabres.... GMBots has already committed to Linus so to spend assets to trade for Grubs or any other goalie would be a fools errand;
3. No reason for GMBots to deal ROR for that type of return.... he will expect to be overpaid in order to move ROR.... ROR offers everything that GMBots wants at this point a legit #2C who can help develop Mittelstadt into a future #2C..... allows Mittelstadt the year to mature and learn what it takes to be a #2C in the NHL;
4. NYR have no reason to make the Spooner trade..... the NYR are in a similar situation as the Sabres so trading between the two teams is a tough hill to climb.... to move Beaulieu you need to find a team that would want to try him as a bottom pair Dman at very low cost (meaning the Sabres will be retaining $1,200,000 if they expect to get anything of value in return).... the Sabres can afford to retain in 18/19.... try a team that is up against the cap;

you clearly don't understand how RFA works, if the sabres can't get a decent trade for Lehner they will tender him a qualifying offer, I think they would be completely fine with keeping Lehner another year at 4mil, If anyone then sends an offer sheet on him its going to be over 4 mil so that team would have to give up a 1st and a 3rd as compensation offer sheets between $3,925,975 to $5,888,960 yield First and third-round picks.

So either the Sabres get a nice package for the RFA rights, They get a First and a 3rd or they retain Robin Lehner have have a perfect Swedish tandem in Lehner and Ullmark. I honestly want them to keep him.