[R-pkg-devel] Two (newbie/luser) questions about adding CI to github hosted package

I would be very grateful of help as I seem to be making very heavy weather of all the intricacies of creating a 
robust R package that might be useful (mainly to R newbies/lusers of even lower R/programming skills than mine). 

I am making a lot of progress and am awed by the work so many have put in to make things possible: huge gratitude 
to too many to name. However, I seem to be hitting a wall on adding CI to my package. 

1) I am sure that linting my package will help me but there are some defaults in lintr/superlinter that I am want
to take a personal stand and not use: allowing myself not always to use perfect camelCase because I think it will
confuse my end users and the line length limit which at the default of 80 seems to me, on a modern set up, to make
my code far less readable than if I allow some long lines. My problem is that I am failing to work out how to override
the defaults. I thought that putting in /TEMPLATES/.lintr in my package directory and having it contain:

# linters: with_defaults(object_usage_linter = NULL)
linters: with_defaults(
  line_length_linter(120),
  cyclocomp_linter(25),
  object_name_linter = NULL
  )
would override the defaults (I'm working on the cyclocomp complaint!)  Can anyone, perhaps looking at my 
https://github.com/cpsyctc/CECPfuns/ package, tell me what I'm doing wrong and how to get it right?!

2) I work on a machine running Ubuntu 20.04 in Rstudio and everything checks and tests fine there but I wanted
to use the github actions to check the package out on Windows and Mac and, rather more by luck I think than really
understanding how I got there, I seem to have achieved that.  Rather bizarrely, the code (it's only R source)
passes on Windows and Mac but fails in the Ubuntu test systems with errors like:

?? R CMD build ?????????????????????????????????????????????????????????????????
* checking for file ?.../DESCRIPTION? ... OK
* preparing ?CECPfuns?:
* checking DESCRIPTION meta-information ... OK
* installing the package to process help pages
      -----------------------------------
* installing *source* package ?CECPfuns? ...
** using staged installation
** R
** inst
** byte-compile and prepare package for lazy loading
Error in dyn.load(file, DLLpath = DLLpath, ...) : 
  unable to load shared object '/home/runner/work/_temp/Library/stringi/libs/stringi.so':
  libicui18n.so.55: cannot open shared object file: No such file or directory
Calls: <Anonymous> ... namespaceImport -> loadNamespace -> library.dynam -> dyn.load
Execution halted
ERROR: lazy loading failed for package ?CECPfuns?

I _think_ these are just changes in the stirngi package that seem to failing on the test machine
and OK on my machine. That made me think that I can see a lot of logic in my checking things on
the various default versions of R in Ubuntu 16.04, Windows and MacOS but perhaps it is unnecessary
and wasting resources to check the release version of R on Ubuntu 20.04 as it seems safe enough to
assume that the package built on my local machine in the release version of R and on Ubuntu 20.04
that fails like this will only be transient (or that successes on my machine will only be ... but
at least I'll see them and not waste github resources!)

The catch is that I am baffled by how to configure github actions to change the lint defaults and
to change the selection of releases and platforms.  I think that may because I may have created
a mess in my github actions workflows.

Would anyone be willing to help or even to look at it and point me to the explanations I am failing
to find?! 

TIA,

Chris