Those lines are OK, only that instead of localhost, should be an IP like 10.x.x.x
Maybe you just add some extra spaces in the file, you should always use nano editor and be sure you do not put extra spaces or lines or other characters
Even a wrong color RGB code can make that lnd do not start.
You can stop umbrel, rename that old lnd.conf in something else and then restart the umbrel scripts. lnd.conf will be created again, clean.
Here you have an example of full lnd.conf from an umbrel (the last 2 are optional and the IPs replace them with yours ones):
[Application Options]
listen=0.0.0.0:9735
rpclisten=0.0.0.0:10009
restlisten=0.0.0.0:8080
maxpendingchannels=3
minchansize=500000
accept-keysend=true
tlsextraip=10.21.x.x
tlsextradomain=umbrel.local
tlsautorefresh=1
tlsdisableautofill=1
feeurl=
allow-circular-route=1
alias=YourFunnyAliasNode
color=#5f1be8
# Mark unpayable, unpaid invoices as deleted
gc-canceled-invoices-on-startup=1
gc-canceled-invoices-on-the-fly=1
# Avoid historical graph data sync
ignore-historical-gossip-filters=1
# Avoid slow startup time
sync-freelist=1
# Avoid high startup overhead
stagger-initial-reconnect=1
[Bitcoind]
bitcoind.rpchost=10.21.x.x
bitcoind.rpcuser=umbrel
bitcoind.rpcpass=longcharspassword
bitcoind.zmqpubrawblock=tcp://10.21.x.x:28332
bitcoind.zmqpubrawtx=tcp://10.21.x.x:28333
[Bitcoin]
bitcoin.active=1
bitcoin.mainnet=1
# Default to neutrino as the node is
# automatically switched to bitcoind once
# IBD is complete
bitcoin.node=bitcoind
bitcoin.defaultchanconfs=2
# [neutrino]
# Testnet neutrino peers that are automatically
# uncommented if Umbrel is configured for testnet
# neutrino.addpeer=testnet1-btcd.zaphq.io
# neutrino.addpeer=testnet2-btcd.zaphq.io
[tor]
tor.active=1
tor.control=10.21.x.x:29051
tor.socks=10.21.x.x:9050
tor.targetipaddress=10.21.x.x
tor.password=longcharspassword
tor.v3=1
[wtclient]
wtclient.active=true
wtclient.sweep-fee-rate=10
[protocol]
protocol.no-anchors=true
NOTE: if you just want to reset the lnd.conf file with a default one, you can do this
Make a backup of your current lnd.conf
cp ~/umbrel/lnd/lnd.conf ~/umbrel/lnd/lnd.bak
Delete your current lnd.conf, re-configure Umbrel and restart the node
rm ~/umbrel/lnd/lnd.conf && ~/umbrel/scripts/configure && sudo reboot
After is all OK, you can go and add one by one the lines you want in your lnd.conf, but be careful to not broke it again with wrong info.